some improvement to the Update / create event pages

- i18n of all the form
- add a title to each page
- chill layout of each page
- add flash message on successfully creation and update action

For the update page, (see #23), the user is not allowed to update
the center

close #23
close #2

Controller/EventController.php

@@ -41,6 +41,9 @@ class EventController extends Controller
             $em = $this->getDoctrine()->getManager();
             $em->persist($entity);
             $em->flush();
+            
+            $this->addFlash('success', $this->get('translator')
+                    ->trans('The event was created'));
 
             return $this->redirect($this->generateUrl('chill_event__event_show', array('event_id' => $entity->getId())));
         }
@@ -186,6 +189,7 @@ class EventController extends Controller
             'method' => 'PUT',
         ));
 
+        $form->remove('center');
 
         $form->add('submit', 'submit', array('label' => 'Update'));
 
@@ -211,6 +215,9 @@ class EventController extends Controller
 
         if ($editForm->isValid()) {
             $em->flush();
+            
+            $this->addFlash('success', $this->get('translator')
+                    ->trans('The event was updated'));
 
             return $this->redirect($this->generateUrl('chill_event__event_edit', array('event_id' => $event_id)));
         }