Order cancellations by cancellation date

Closes #616

website/events/models.py

@@ -151,29 +151,36 @@ class Event(models.Model, metaclass=ModelTranslateMeta):
         return self.registrationinformationfield_set.count() > 0
 
     def reached_participants_limit(self):
+        """Is this event up to capacity?"""
         return (self.max_participants is not None and
                 self.max_participants <= self.registration_set.filter(
                     date_cancelled=None).count())
 
     @property
     def registrations(self):
+        """Queryset with all non-cancelled registrations"""
         return self.registration_set.filter(date_cancelled=None)
 
     @property
     def participants(self):
+        """Return the active participants"""
         if self.max_participants is not None:
             return self.registrations.order_by('date')[:self.max_participants]
         return self.registrations.order_by('date')
 
     @property
     def queue(self):
+        """Return the waiting queue"""
         if self.max_participants is not None:
             return self.registrations.order_by('date')[self.max_participants:]
         return []
 
     @property
     def cancellations(self):
-        return self.registration_set.exclude(date_cancelled=None)
+        """Return a queryset with the cancelled events"""
+        return (self.registration_set
+                .exclude(date_cancelled=None)
+                .order_by('date_cancelled'))
 
     @property
     def registration_allowed(self):