TST: remove test_yahoo options test skipping

[jreback]

closes #4028

just a reversal of the warnings - seem ok now

[cpcloud]

merge?

[cpcloud]

2 to go!

[jreback]

yerp

[jtratner]

This is still failing for me:

======================================================================
FAIL: test_options (pandas.io.tests.test_yahoo.TestYahoo)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "../pandas/pandas/util/testing.py", line 769, in network_wrapper
    return t(*args, **kwargs)
  File "../pandas/pandas/io/tests/test_yahoo.py", line 120, in test_options
    assert len(calls)==5
AssertionError

[jreback]

this works when I run it at the command line.....any reason you can think why this sometimes fails?

[cpcloud]

@jreback pull down my data-reader-test branch. you should be able to repro the failure there if you do git reset --hard HEAD~1 and then run the test suite. it fails because there's a call to dropna without the all argument and the bid and asking price columns are all nans.

[cpcloud]

i've separated all of the tests so that failures are more isolated and we can tell wtf is going on. before that, everything was bundled together in just a few test functions, maybe i'll write something on the wiki about isolating tests as much as possible