Replace direct use of testtools BaseTestCase.

Using the BaseTestCase across the tests in the tree lets us put in log
fixtures and consistently handle mox and stubout.

Part of blueprint grizzly-testtools.

Change-Id: Iba7eb2c63b0c514009b2c28e5930b27726a147b0

tests/unit/test_gettext.py

@@ -16,15 +16,15 @@
 #    under the License.
 
 import logging
-import testtools
 
 from openstack.common.gettextutils import _
+from tests import utils
 
 
 LOG = logging.getLogger(__name__)
 
 
-class GettextTest(testtools.TestCase):
+class GettextTest(utils.BaseTestCase):
 
     def test_gettext_does_not_blow_up(self):
         LOG.info(_('test'))