Images API v2.0 Tenant Permisions on Image Life Cycle Test

Implements tenant permissions on image life cycle test:
 - added image life cycle tenant permission test.

Refactors tenant permissions on image life cycle test:
 - made changes as per the refactoring done on image model, client and fixtures.
 - added new test steps to complete the permission cycle.

Change-Id: I2a76fcd4e5273d212a4ef6e716ed0ae3f3771ca0
Merge "Images API v2.0 Tenant Permisions on Image Life Cycle Test"