glusterfs: add missing i18n import

Also remove unnecessary fake _ function
from the test suite so that other possible
occurrences of this genre of bug would be
detected by unit tests.

Change-Id: I8292fceda02442f83210e98cee4619c81bc181e5
Closes-Bug: #1506297

manila/share/drivers/glusterfs/__init__.py

@@ -32,6 +32,7 @@ from oslo_config import cfg
 from oslo_log import log
 
 from manila import exception
+from manila.i18n import _
 from manila.i18n import _LE
 from manila.share import driver
 from manila.share.drivers import ganesha

manila/tests/__init__.py

@@ -29,10 +29,5 @@
 """
 
 import eventlet
-from six.moves import builtins
 
 eventlet.monkey_patch()
-
-# See http://code.google.com/p/python-nose/issues/detail?id=373
-# The code below enables nosetests to work with i18n _() blocks
-setattr(builtins, '_', lambda x: x)