Add support for rbd-backed volumes to ::all class

The openstack::all class currently only supports the iscsi
backend for Cinder.  This commit allows users to specify
that Cinder volumes should be backed by Ceph RBD instead
by specifying a different volume driver and other necessary
Ceph information.

Change-Id: I53232201fdd9a1fb5007f15005eca69424275183
Implements: blueprint ceph-all-in-one
Merge "Add support for rbd-backed volumes to ::all class"