Added Cinder volume backup to Ceph support

Added new Ceph backup service to allow backup
of Cinder volumes to a Ceph object store. This
driver is compatible with the existing backup
interface provided by the Swift backup service.

Implements: blueprint cinder-backup-to-ceph

Change-Id: I299f033347cb263e7169c4a4efb758d19e753f46
Merge "Added Cinder volume backup to Ceph support"