Summary: LibvirtStorageAdaptor.getPhysicalDisk() to recogize .raw extension

Detail: getPhysicalDisk() was not matching on volumes with .raw, so
instead setting disk format to QCOW2.

BUG-ID: CLOUDSTACK-5018
Bugfix-for:
Reviewed-by:
Reported-by:
Signed-off-by: John Kinsella <jlk@stratosec.co> 1383287538 -0700