Adding ceph as backup backed for cinder

The patch adds new classes to be used in case of
usage ceph as backup backend for cinder.

Change-Id: I8e9d9387101118e4eaf8243f55ba54703faa00a0
Related-PROD: PROD-26190
(cherry picked from commit 69b5e415b214a4b4fa83e75022c6fe2035c1539c)
2 files changed