Image API v2.0 Image Model, Client and Tests - Refactoring .

Refactors image model:
 - added Images class
 - corrected the key name - change 'member_id' to 'member' in '_obj_to_json' method
 - improved the implementation of '_list_to_obj()' method for Images class to now return an Images instance.

Refactors image client:
 - fixed serialization and deserialization issues in 'list_images()' method

Refactors member(s) tests:
 - fixed string to date object conversion issues.

Change-Id: I690409930fc50822289500ae898f27a6c791f120
Merge "Image API v2.0 Image Model, Client and Tests - Refactoring ."