Images API v2.0 Image Sharing, Deletion and Accessibility Cycle

Implements image sharing, deletion and accessibility cycle test:
 - added new test scenario: image sharing, deletion and accessibility cycle.
 - refactored image fixtures.
 - reverted changes on image fixtures and made it a separate PR.
 - improved naming of variables.

Refactors the tests and adds tags.

Change-Id: I01509aca865dca316e75dc8342574fa7affa4467
Merge "Images API v2.0 Image Sharing, Deletion and Accessibility Cycle"