Use mox3 rather than mox

mox3 is a port of mox to Python 3, and it's also compatible with Python 2.6 and
2.7.

Partial-Bug: 1287323
Change-Id: I6caad9da450a6821ba5d2dab607106ddf9d743fd

openstack_auth/tests/tests.py

@@ -13,7 +13,7 @@
 
 import copy
 
-import mox
+from mox3 import mox
 
 from django import test
 from django.conf import settings

test-requirements.txt

@@ -1,6 +1,6 @@
 hacking>=0.8.0,<0.9
 Babel>=1.3
 coverage>=3.6
-mox>=0.5.3
+mox3>=0.7.0
 sphinx>=1.1.2,<1.2
 oslo.sphinx