BUG: Fred tests failing - possible error with Fred data IO.
These two tests are failing (but they've been hidden for a while). They are (going to be) skipped on master for the moment, but need to be fixed/removed at some pont.

Is someone responsible/using the Fred data reader right now?

```
======================================================================
ERROR: test_fred_nan (pandas.io.tests.test_data.TestFred)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.0.0-py2.7-linux-x86_64.egg/pandas/util/testing.py", line 842, in network_wrapper
    return t(*args, **kwargs)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.0.0-py2.7-linux-x86_64.egg/pandas/io/tests/test_data.py", line 387, in test_fred_nan
    assert pd.isnull(df.ix['2010-01-01'])
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.0.0-py2.7-linux-x86_64.egg/pandas/core/generic.py", line 559, in __nonzero__
    raise ValueError("The truth value of an array is ambiguous. Use a.empty, a.item(), a.any() or a.all().")
ValueError: The truth value of an array is ambiguous. Use a.empty, a.item(), a.any() or a.all().
-------------------- >> begin captured stdout << ---------------------
Failed: ValueError('The truth value of an array is ambiguous. Use a.empty, a.item(), a.any() or a.all().',)
--------------------- >> end captured stdout << ----------------------
```

```
======================================================================
ERROR: test_fred_parts (pandas.io.tests.test_data.TestFred)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.0.0-py2.7-linux-x86_64.egg/pandas/util/testing.py", line 842, in network_wrapper
    return t(*args, **kwargs)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.0.0-py2.7-linux-x86_64.egg/pandas/io/tests/test_data.py", line 394, in test_fred_parts
    self.assertEqual(df.ix['2010-05-01'], 217.23)
  File "/usr/lib/python2.7/unittest/case.py", line 511, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/usr/lib/python2.7/unittest/case.py", line 501, in _baseAssertEqual
    if not first == second:
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.0.0-py2.7-linux-x86_64.egg/pandas/core/generic.py", line 559, in __nonzero__
    raise ValueError("The truth value of an array is ambiguous. Use a.empty, a.item(), a.any() or a.all().")
ValueError: The truth value of an array is ambiguous. Use a.empty, a.item(), a.any() or a.all().
-------------------- >> begin captured stdout << ---------------------
Failed: ValueError('The truth value of an array is ambiguous. Use a.empty, a.item(), a.any() or a.all().',)
--------------------- >> end captured stdout << ----------------------
----------------------------------------------------------------------
```
