Test failures on debian sid
Hi, I'm testing the current pandas master on debian sid with updated numexpr and PyTables from experimental and I'm experimenting some test failures:

```
$ env PYTHONPATH=. nosetests pandas
.................................EES.FSSS......................................................S.............F..........................SSSS...SS.......................S........................................................................................................................................................................................................................................................................................................................................................S.......................................................................................................................SSSS..........................S.............................................................SSSSSSSSSS....................SS...................................................................................................................................................S...............................S.......................SSSSSSS.........................................F..............................................S....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
E...................................................................................................................................................................................................................................................S........................................................................................................................................................................S..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................S.................................................................................S.S...............S.S............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................S.............................................................................................S..............................................................................................................................................................................S...S............SSS.........S............SS............SS.....SSSS.................................................................................................................................................................................................................S.......................................................................................................................................................................................................................
======================================================================
ERROR: test_get_goog_volume (pandas.io.tests.test_data.TestGoogle)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/antonio/pandas/pandas/util/testing.py", line 857, in network_wrapper
    return t(*args, **kwargs)
  File "/home/antonio/pandas/pandas/io/tests/test_data.py", line 55, in test_get_goog_volume
    self.assertEqual(df.Volume.ix['OCT-08-2010'], 2863473)
  File "/home/antonio/pandas/pandas/core/indexing.py", line 54, in __getitem__
    return self._getitem_axis(key, axis=0)
  File "/home/antonio/pandas/pandas/core/indexing.py", line 631, in _getitem_axis
    return self._get_label(key, axis=axis)
  File "/home/antonio/pandas/pandas/core/indexing.py", line 1273, in _get_label
    return self.obj[key]
  File "/home/antonio/pandas/pandas/core/series.py", line 920, in __getitem__
    return self.index.get_value(self, key)
  File "/home/antonio/pandas/pandas/tseries/index.py", line 1184, in get_value
    raise KeyError(key)
KeyError: 'OCT-08-2010'
-------------------- >> begin captured stdout << ---------------------
Failed: KeyError('OCT-08-2010',)

--------------------- >> end captured stdout << ----------------------

======================================================================
ERROR: test_get_multi1 (pandas.io.tests.test_data.TestGoogle)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/antonio/pandas/pandas/util/testing.py", line 857, in network_wrapper
    return t(*args, **kwargs)
  File "/home/antonio/pandas/pandas/io/tests/test_data.py", line 68, in test_get_multi1
    testit()
  File "/home/antonio/pandas/pandas/io/tests/test_data.py", line 64, in testit
    self.assertEquals(ts[0].dayofyear, 96)
  File "/home/antonio/pandas/pandas/tseries/index.py", line 1298, in __getitem__
    val = arr_idx[key]
IndexError: index 0 is out of bounds for axis 0 with size 0
-------------------- >> begin captured stdout << ---------------------
Failed: IndexError('index 0 is out of bounds for axis 0 with size 0',)

--------------------- >> end captured stdout << ----------------------

======================================================================
ERROR: test_axis_limits (pandas.tseries.tests.test_plotting.TestTSPlot)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/antonio/pandas/pandas/tseries/tests/test_plotting.py", line 344, in test_axis_limits
    _test(ax)
  File "/home/antonio/pandas/pandas/tseries/tests/test_plotting.py", line 308, in _test
    ax.get_figure().canvas.draw()
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 349, in draw
    tkagg.blit(self._tkphoto, self.renderer._renderer, colormode=2)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/tkagg.py", line 20, in blit
    tk.call("PyAggImagePhoto", photoimage, id(aggimage), colormode, id(bbox_array))
TclError: this isn't a Tk application

======================================================================
FAIL: test_google (pandas.io.tests.test_data.TestGoogle)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/antonio/pandas/pandas/util/testing.py", line 857, in network_wrapper
    return t(*args, **kwargs)
  File "/home/antonio/pandas/pandas/io/tests/test_data.py", line 42, in test_google
    13.68)
AssertionError: 17.66 != 13.68
-------------------- >> begin captured stdout << ---------------------
Failed: AssertionError('17.66 != 13.68',)

--------------------- >> end captured stdout << ----------------------

======================================================================
FAIL: test_invalid_url (pandas.io.tests.test_html.TestReadHtmlBase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/antonio/pandas/pandas/util/testing.py", line 857, in network_wrapper
    return t(*args, **kwargs)
  File "/home/antonio/pandas/pandas/io/tests/test_html.py", line 299, in test_invalid_url
    'http://www.a23950sdfa908sd.com')
AssertionError: No tables found
-------------------- >> begin captured stdout << ---------------------
Failed: AssertionError('No tables found',)

--------------------- >> end captured stdout << ----------------------

======================================================================
FAIL: testWLS (pandas.stats.tests.test_ols.TestOLS)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/antonio/pandas/pandas/stats/tests/test_ols.py", line 111, in testWLS
    self._check_wls(X, Y, weights)
  File "/home/antonio/pandas/pandas/stats/tests/test_ols.py", line 134, in _check_wls
    self.checkMovingOLS('rolling', x, y, weights=weights)
  File "/home/antonio/pandas/pandas/stats/tests/test_ols.py", line 208, in checkMovingOLS
    result_index=n)
  File "/home/antonio/pandas/pandas/stats/tests/test_ols.py", line 247, in compare
    assert_almost_equal(ref, res)
  File "/home/antonio/pandas/pandas/util/testing.py", line 198, in assert_almost_equal
    assert_almost_equal(a[i], b[i], check_less_precise)
  File "/home/antonio/pandas/pandas/util/testing.py", line 227, in assert_almost_equal
    1, a / b, decimal=decimal, err_msg=err_msg(a, b), verbose=False)
  File "/usr/lib/pymodules/python2.7/numpy/testing/utils.py", line 468, in assert_almost_equal
    raise AssertionError(msg)
AssertionError: 
Arrays are not almost equal to 5 decimals expected 6.61194 but got 7.66003
-------------------- >> begin captured stdout << ---------------------
Make sure you're using statsmodels 0.5.0.dev-cec4f26 or later.

--------------------- >> end captured stdout << ----------------------

----------------------------------------------------------------------
Ran 3933 tests in 407.389s

FAILED (SKIP=64, errors=3, failures=3)
```

Some cfg info:

```
PyTables version:  3.0.0
HDF5 version:      1.8.11
NumPy version:     1.7.1
Numexpr version:   2.2 (not using Intel's VML/MKL)
Python version:    2.7.5+ (default, Sep 17 2013, 15:31:50)  [GCC 4.8.1]
Platform:          linux2-x86_64
```
