Add missing validateQemuReadable to oop

Change-Id: I6598619c7acd18e41b51c15018627973f1eb263a
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1114499
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/29398
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Yedidyah Bar David <didi@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/29425
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>