TestDataFrameFormatting error when stty columns = 0
When stty columns = 0, I guess this test error.

```
======================================================================
FAIL: test_auto_detect (pandas.tests.test_format.TestDataFrameFormatting)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/tests/test_format.py", line 315, in test_auto_detect
    self.assertTrue(has_expanded_repr(df))
AssertionError: False is not true
```

To reproduce:

```
stty columns 0
nosetests pandas.tests.test_format
```
