vdsm.spec: vdsm should own vdsm.log

/var/log/vdsm/vdsm.log should be owned by VDSM.

Change-Id: Id12a78f3243138cd95a13cc7c8a8d3d499ceee4a
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1061561
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/24042
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>