Updated openstack/openstack
Project: openstack/tempest  4b77b5e44c3fc6c44202012e32f9e04f2c758457

Use python abc in auth class

Instead of using NotImplementedError the abc class has the advantage
that it fails faster if a class doesn't implement the needed interface.
Adapt unit test and test class.

Change-Id: Ide914a4bb577a28a3d202cbf088c404323a29b21
Partial-Bug: #1346797