image membership tests

Depends on
Change-Id: I4a892c001ab312000ce59da59c73d3a75316963e

 - refactored datagen package import
 - added extra assertions to test_remove_member
 - fixed duplicate tests
 - removed hard-coded urls, instead getting them from config
 - some refactoring for clarity in response to comments
 - porting image membership tests from tempest
 - adding tenant_client to fixtures

Change-Id: I270ad24c4d82bc31fb5b07ea05bc84458844143e
adding images api v2.0 tests

Depends on
Change-Id: Ifb0f895a2d9d18bad6e912c9b446394c1a94ad73

 - rebased and updated directory structure for merging
 - fixed some indentation & rebased with new master
 - wrote additional tests to have parity with tempest
 - fleshed out fixture and added first test
 - cherry-picked from fast-forward commit

Change-Id: Ia889aec302f2f43d3a1ffbb1b63ad59b85fc4133
Adding to functional tests for orders

Change-Id: I67a8e7ab92e64eddb1d730d74fd3b1e2dbb05072
Merge "adding images api v2.0 tests"
Merge "image membership tests"