test_set_locale fails if LC_ALL is set outside
```
~/pandas-0.16.2+git58-g01995b2# LC_ALL=C.UTF-8 nosetests3 -s -v /tmp/buildd/pandas-0.16.2+git58-g01995b2/debian/tmp/usr/lib/python3/dist-packages/pandas/tools/tests/test_util.py
test_datetimeindex (pandas.tools.tests.test_util.TestCartesianProduct) ... ok
test_simple (pandas.tools.tests.test_util.TestCartesianProduct) ... ok
test_get_locales (pandas.tools.tests.test_util.TestLocaleUtils) ... ok
test_get_locales_prefix (pandas.tools.tests.test_util.TestLocaleUtils) ... ok
test_set_locale (pandas.tools.tests.test_util.TestLocaleUtils) ... FAIL

======================================================================
FAIL: test_set_locale (pandas.tools.tests.test_util.TestLocaleUtils)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/buildd/pandas-0.16.2+git58-g01995b2/debian/tmp/usr/lib/python3/dist-packages/pandas/tools/tests/test_util.py", line 90, in test_set_locale
    self.assertEqual(current_locale, CURRENT_LOCALE)
AssertionError: Tuples differ: (None, None) != ('en_US', 'UTF-8')

First differing element 0:
None
en_US

- (None, None)
+ ('en_US', 'UTF-8')

----------------------------------------------------------------------
Ran 5 tests in 0.047s

FAILED (failures=1)

~/pandas-0.16.2+git58-g01995b2# nosetests3 -s -v /tmp/buildd/pandas-0.16.2+git58-g01995b2/debian/tmp/usr/lib/python3/dist-packages/pandas/tools/tests/test_util.py
test_datetimeindex (pandas.tools.tests.test_util.TestCartesianProduct) ... ok
test_simple (pandas.tools.tests.test_util.TestCartesianProduct) ... ok
test_get_locales (pandas.tools.tests.test_util.TestLocaleUtils) ... ok
test_get_locales_prefix (pandas.tools.tests.test_util.TestLocaleUtils) ... ok
test_set_locale (pandas.tools.tests.test_util.TestLocaleUtils) ... ok

----------------------------------------------------------------------
Ran 5 tests in 0.039s

OK
```

and I need to set LC_ALL so that tests like read_html pass while decoding unicode correctly
