Minor fixes for closing accompanying course:

* check that transition can be applyied in menu;
* change organisation for activityVoter, and check for authorization in
    Activity Controller
* fix label 'create' in accompanying course document
* minor fix in accompanying course document voter
* change color when course is closed and show old user, and startdate /
    enddate

src/Bundle/ChillActivityBundle/Controller/ActivityController.php

@@ -269,8 +269,7 @@ final class ActivityController extends AbstractController
 
         }
 
-        // TODO revoir le Voter de Activity pour tenir compte qu'une activité peut appartenir a une période
-        // $this->denyAccessUnlessGranted('CHILL_ACTIVITY_CREATE', $entity);
+        $this->denyAccessUnlessGranted(ActivityVoter::CREATE, $entity);
 
         $form = $this->createForm(ActivityType::class, $entity, [
             'center' => $entity->getCenter(),