vm, guestagent: return hash should include also the disk mapping

Change-Id: I148196ccf353613f9cffed7753e7100bd1dd30de
Signed-off-by: Liron Aravot <laravot@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/31701
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>