rdv: add default status on rdv when creating a new rdv

src/Bundle/ChillCalendarBundle/Entity/Calendar.php

@@ -23,6 +23,10 @@ use Chill\CalendarBundle\Repository\CalendarRepository;
  */
 class Calendar
 {
+    const STATUS_VALID = 'valid';
+    const STATUS_CANCELED = 'canceled';
+    const STATUS_MOVED = 'moved';
+
     /**
      * @ORM\Id
      * @ORM\GeneratedValue