Use mock in test_policy
Use mock in test_policy

FakePolicyEnforcer is trying to imitate the real policy enforcer.
We don't need it in the test_policy tests.

fixes bug 1243902

Change-Id: Id82d09dc9aafbf57b6fc968ae1ded944b8d64229

dims/glance,cloudbau/glance,JioCloud/glance,openstack/glance,klmitch/glance,darren-wang/gl,scripnichenko/glance,rajalokan/glance,saeki-masaki/glance,sigmavirus24/glance,klmitch/glance,akash1808/glance,dims/glance,ozamiatin/glance,tanglei528/glance,stevelle/glance,stevelle/glance,openstack/glance,rajalokan/glance,takeshineshiro/glance,scripnichenko/glance,jumpstarter-io/glance,saeki-masaki/glance,jumpstarter-io/glance,JioCloud/glance,wkoathp/glance,kfwang/Glance-OVA-OVF,cloudbau/glance,wkoathp/glance,ozamiatin/glance,sigmavirus24/glance,vuntz/glance,kfwang/Glance-OVA-OVF,openstack/glance,darren-wang/gl,akash1808/glance,redhat-openstack/glance,paramite/glance,paramite/glance,takeshineshiro/glance,vuntz/glance,redhat-openstack/glance,tanglei528/glance