Replace UserManager/TenantManager with None in tests
Replace UserManager/TenantManager with None in tests

UserManager/TenantManager seems private classes in keystoneclient
and the interface was changed in keystoneclient 0.10.0.
django-openstack-auth tests actually don't need these managers,
so this commit makes test data not use these classes.

Change-Id: I9398c705acab262e89d4801da84ccea188980d99
Closes-Bug: #1349485

promptworks/django_openstack_auth,ashokkumarprajapati/openstack_auth_remote,redhat-openstack/django_openstack_auth,dan1/django_openstack_auth_proto,ging/django_openstack_auth,redhat-openstack/django_openstack_auth,dan1/django_openstack_auth_proto,promptworks/django_openstack_auth,ging/django_openstack_auth,jamielennox/django_openstack_auth