system test for Ceph deployment and HA

 * 2 multi-node and 1 HA configuration is deployed with Ceph enabled
 * Ceph HA test simulates OSD and Monitor failures
 * prepare_environment() is extended to skip post-deploy snapshot
   (clock skew introduced by snapshotting the env breaks Ceph cluster)

Change-Id: Id78ba3911d2cbbafbac9ac1414083e32a7a22639