vhosts: Don't shadow "post-network-setup".

If useSnakeOil was enabled, and the // operator doesn't do a deep
override, the whole systemd attribute set was replaced by the snakeoil
key injector service.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
xmpp: Deactivate ejabberd_service listeners.

Those are not available in MongooseIM so we need to either find a
replacement or bring it back into MongooseIM.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
xmpp: Disable mod_admin_extra.

This was removed back in version 1.2.2 and was later
(esl/ejabberd@d8c56c1) re-added, so we just need to either wait for the
next release or patch it in by ourselves.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>