Blocking version 1.1.6 of django_openstack_auth

The release of django_openstack_auth 1.1.6 introduced a change that
is not compatible with the stable/icehouse release. All gate jobs
are blocked until this is fixed.

Close-Bug: #1332855
Change-Id: I0f91df1e4b072a0d5c1360487078ef03eb731561