Reload daemon file after each install

Currently we load the daemon file only on first install. After upgrade
we could fail with:
"Warning: Unit file changed on disk, 'systemctl --system daemon-reload'
recommended."

This patch perform the reload after each installation of vdsm.

Change-Id: I1d6e6e292494da78052a9593c5cbe94ac35ea0d9
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1063772
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/24535
Reviewed-by: Dan Kenigsberg <danken@redhat.com>