trival change for skip mom test logic

    using wrapper of runtime vdsm caps to judge mom module existence
instead of trying to load, make it usable for other testcases outside
this module.

Change-Id: Iee2adb63d61f708d74ef84ee68f220994247eea3
Signed-off-by: Royce Lv<lvroyce@linux.vnet.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/12550
Tested-by: Mei Liu <liumbj@linux.vnet.ibm.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>