Configure and enable the graceperiod plugin on upgrades
    
    The graceperiod plugin was only being enabled on new
    installations. Enable also on upgrade.
    
    Loading a new plugin requires a restart. Do so if a
    new one is configured.
    
    Fixes: https://pagure.io/freeipa/issue/1539
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>