Feature/provenance

Test missing but code can be checked

smash/web/forms/appointment_form.py

@@ -32,7 +32,7 @@ class AppointmentForm(ModelForm):
     def register_changes(self):
         self.changes = []
         for field in self.changed_data:
-            new_value = self.cleaned_data[field]
+            new_value = self.cleaned_data[field] or self.data[field]
             if isinstance(new_value, QuerySet):
                 new_human_values = '; '.join([str(element) for element in new_value]) 
                 new_value = ','.join([str(element.id) for element in new_value]) #overwrite variable