sos/vdsm.py: Collect /etc/vdsm permission

An user complained that vdsm failed to start on his
machine. It was finally tracked down to his /etc/vdsm missing read
permissions for vdsm. Let us collect /etc/vdsm permission so it is
easier to pinpoint for the next user.

Change-Id: I17371a82340f64df285bb4dda650e571899ca02f
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/19227
Reviewed-by: Dan Kenigsberg <danken@redhat.com>