add the twig date extension

The twig date extension allow to print message like "update 1 hour ago".

Documentation here : http://twig.sensiolabs.org/doc/extensions/date.html

Resources/config/services.yml

@@ -28,6 +28,13 @@ services:
         class: Twig_Extensions_Extension_Intl
         tags: 
             - { name: twig.extension }
+            
+    twig_date:
+        class: Twig_Extensions_Extension_Date
+        arguments:
+            - "@translator"
+        tags: 
+            - { name: twig.extension }
 
     chill.main.form.type.translatable.string:
         class: Chill\MainBundle\Form\Type\TranslatableStringFormType