vdsm-tool: update wording of libvirt/supervdsm restart message

Update wording of message telling the user what to run in order to
restart libvirt and supervdsmd.

Change-Id: I92153989525a9bda681c75f1dabc21911d1054a0
Signed-off-by: Greg Padgett <gpadgett@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/19422
Reviewed-by: Dan Kenigsberg <danken@redhat.com>