Add support for rbd in glance

Add support for Ceph/rbd in glance.
Unit test added to spec.

Add package dependency "python-ceph" accordingly to a patch from
Michael Jeanson <mjeanson@gmail.com>.

Change-Id: I0908cde951994db6aba74d2ce3415126c429a76e
Merge "Add support for rbd in glance"