Fix tests failing if keystone is running locally
Fix tests failing if keystone is running locally

This mocks out the call to python-keystoneclient's Session.get_token(),
preventing any actual calls being made to a keystone service, running or
not.

Change-Id: I24b0874d8e67b46b7c2294d4ac54efa861561dff
Closes-bug: 1423170

mmasaki/python-glanceclient,openstack/python-glanceclient,openstack/python-glanceclient,varunarya10/python-glanceclient,mmasaki/python-glanceclient,klmitch/python-glanceclient,JioCloud/python-glanceclient,JioCloud/python-glanceclient,klmitch/python-glanceclient,varunarya10/python-glanceclient