TST: Fix timezone test to avoit dateutil issue
Closes #7993.

this doesn't seem to fix the test on windows though.....
 ```

C:\Users\Jeff Reback\Documents\GitHub\pandas>git checkout sinhrks-gh7993
Switched to branch 'sinhrks-gh7993'

C:\Users\Jeff Reback\Documents\GitHub\pandas>git diff master
diff --git a/pandas/tseries/tests/test_tslib.py b/pandas/tseries/tests/test_tslib.py
index 2cd8539..cdd5170 100644
--- a/pandas/tseries/tests/test_tslib.py
+++ b/pandas/tseries/tests/test_tslib.py
@@ -37,7 +37,7 @@ class TestTimestamp(tm.TestCase):
         import pytz
         import dateutil
         timezones = [(None, 0), ('UTC', 0), (pytz.utc, 0),
-                     ('Asia/Tokyo', 9), ('US/Eastern', -4), ('dateutil/US/Pacific', -7),
+                     ('Asia/Tokyo', 9), ('US/Eastern', -4), ('dateutil/America/Los_Angeles', -7),
                      (pytz.FixedOffset(-180), -3), (dateutil.tz.tzoffset(None, 18000), 5)]

         for date_str, date, expected in tests:

C:\Users\Jeff Reback\Documents\GitHub\pandas>c:\python27-64\python.exe setup.py build
running build
running build_py
copying pandas\version.py -> build\lib.win-amd64-2.7\pandas
copying pandas\tseries\tests\test_tslib.py -> build\lib.win-amd64-2.7\pandas\tseries\tests
running build_ext
skipping 'pandas\index.c' Cython extension (up-to-date)
skipping 'pandas\algos.c' Cython extension (up-to-date)
skipping 'pandas\lib.c' Cython extension (up-to-date)
skipping 'pandas\tslib.c' Cython extension (up-to-date)
skipping 'pandas\parser.c' Cython extension (up-to-date)
skipping 'pandas\hashtable.c' Cython extension (up-to-date)
skipping 'pandas\src\sparse.c' Cython extension (up-to-date)
skipping 'pandas\src\testing.c' Cython extension (up-to-date)
skipping 'pandas\msgpack.cpp' Cython extension (up-to-date)

C:\Users\Jeff Reback\Documents\GitHub\pandas>c:\python27-64\Scripts\nosetests.exe build\lib.win-amd64-2.7\pandas\tseries\tests\test_tslib.py
..........F....................
======================================================================
FAIL: test_repr (pandas.tseries.tests.test_tslib.TestTimestamp)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\Jeff Reback\Documents\GitHub\pandas\build\lib.win-amd64-2.7\pandas\tseries\tests\test_tslib.py", line 162, in test_repr
    self.assertIn(tz_repr, repr(date_tz))
  File "C:\Users\Jeff Reback\Documents\GitHub\pandas\build\lib.win-amd64-2.7\pandas\util\testing.py", line 143, in assertIn
    assert a in b, "%s: %r is not in %r" % (msg.format(a,b), a, b)
AssertionError: : '/US/Pacific' is not in "Timestamp('2014-03-07 00:00:00-0800', tz='dateutil/America/Los_Angeles')"

----------------------------------------------------------------------
Ran 31 tests in 1.407s

FAILED (failures=1)

C:\Users\Jeff Reback\Documents\GitHub\pandas>
```
 Sorry, made mistake. Fixed.
 thanks!
