OpenStack: get identity tests passing in real mode

Updates to the OpenStack identity tests to they pass in both real
and mock modes.

Also, fixes an issue in the delete_user_role request where it
was expecting 200 instead of 204 (which seems to match the
spec and implementation).
Drop 'extras' from tenant test validations.
Merge pull request #1517 from dprince/openstack_identity_test_updates

OpenStack: get identity tests passing in real mode