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

Change-Id: I148196ccf353613f9cffed7753e7100bd1dd30de
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1063597
Signed-off-by: Liron Aravot <laravot@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/33198
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>