image: Set legality of volume to LEGAL after copy

Change-Id: I08733d8361a141ee37dec18c3b9acd8f79e33fae
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=864073
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/12457
Reviewed-by: Ayal Baron <abaron@redhat.com>