PR: 1325095 Multi-backend support. Support for HDD/SSD Pools
PR: 2913 Live migration script issue fixes
   Volume needs to be detached only if its attached.
   Change ownership permissions to nova:nova after mount
PR: 1325095 - Support for NFS backend.
PR: 2913 - Auto mount of NFS file system upon reboot added.
   Used the 'bg' option to retry the mounts if the VM is not
   reachable after boot.
PR: 1336837 Added support for auto start of the nfs live vm.
   The auto start will start all the VMs running in the node.

Change-Id: I0f6473ca935b6a43c35764d9a3fe282c9ab6f275