fix base_url in auth.py

base_url lost a '/' after api version if noversion_path is not None.
this patch set fix the problem

Closes-Bug: #1277792

Change-Id: Id20796e2c00a4722ce78e9e3f7626f0a56317f43
Use testtools.matchers.GreaterThan in test_volumes_transfer

assertGreaterEqual is not in python 2.6 and while I know the long-term
direction for Tempest is to not support 2.6, this change is
super-trivial to make this work on 2.6.

Change-Id: Ie8315b539091f5fbff4e7dfd18a9b824f81a7fb7
Merge "Use testtools.matchers.GreaterThan in test_volumes_transfer"
Merge "fix base_url in auth.py"