TST: option retrieval failures
https://travis-ci.org/pydata/pandas/jobs/26755159

need a better skipping mechanism

```
======================================================================
ERROR: test_get_call_data_warning (pandas.io.tests.test_data.TestOptionsWarnings)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/virtualenv/python3.2.5/lib/python3.2/site-packages/pandas/util/testing.py", line 1281, in wrapper
    return t(*args, **kwargs)
  File "/home/travis/virtualenv/python3.2.5/lib/python3.2/site-packages/pandas/io/tests/test_data.py", line 341, in test_get_call_data_warning
    self.aapl.get_call_data(month=self.month, year=self.year)
  File "/home/travis/virtualenv/python3.2.5/lib/python3.2/site-packages/pandas/io/data.py", line 709, in get_call_data
    return self._get_option_data(month, year, expiry, 9, 'calls')
  File "/home/travis/virtualenv/python3.2.5/lib/python3.2/site-packages/pandas/io/data.py", line 669, in _get_option_data
    " found".format(table_loc, ntables))
IndexError: Table location 9 invalid, 0 tables found
----------------------------------------------------------------------
```
