core: support the newly-tagged vdsm-4.13

vdsm-4.13 would be part of oVirt-3.3.1.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1017285
Change-Id: I12dacd46973cde693105c21ae5bc41aec7fe7863
Signed-off-by: Dan Kenigsberg <danken@redhat.com>