Tenants API User Tests Parity.

1. Added a user test to identity admin package.
2. Renamed test_repo to cloudroast.
3. Refactored fixtures.
4. Fixed reviewer comments - refactored fixtures/test_users.
5. Fixed reviewer comment - fixed assertion issues in test_users.
6. Fixed reviewer comment - flipped up assertEqual as per a suggested best practice.
7. Flipped up addCleanup to first check for a correct response code.
8. Fixed reviewer comment - cleaning up test data.

Change-Id: I71caa15f5537c99506c37aca0554f19b2e75c907
Merge "Tenants API User Tests Parity."