Revert "Force vdsm to stay with libvirt <= 1.2.7"

This is not needed anymore and also breaks live merge.

This reverts commit 93a3d2b9b2fd699e733cb1f19b792137ead28627.

Change-Id: Id08f4e1c61d6b20518570ccafad847ce446fee9d
Signed-off-by: Martin Sivak <msivak@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/32787
Reviewed-by: Dan Kenigsberg <danken@redhat.com>