Prevent ordereddict installation on 2.7

This supports https://review.openstack.org/#/c/48475/ in glance
to remove copy/pasted ordereddict code.

Change-Id: I9b0a2588c6e7da86c048698c5e6dfe37ced4dd7f
Move base test case logic out of __init__.py

It's an antipattern to have functional code in an __init__.py. Move it
into base.py to be less anti.

Change-Id: Ib4db548b78e4e760d94099596a3c495a839836dc
Merge "Prevent ordereddict installation on 2.7"
Merge "Move base test case logic out of __init__.py"