Update images v1 client unittests

Changes to make the metatests for v1 images client pass. Removed
dependency on unittest.Testcase since we're using py.test instead now.

This is in preparation for python-tox gating/integration with jenkins.

Change-Id: I25b1263190edead3b4489a31abd2685efcb99fb2
Update images v2 client unittests

Making metatests pass so that they can be used in gated tox tests later
on.

Change-Id: I7eeed7e05e692001e641fe5bff9b4de8492f946b
Merge "Update images v2 client unittests"
Merge "Update images v1 client unittests"