Add success notification emails.

Enable RevisionMixin for EventAuthorisation.

Add signal receivers for RIGS.

Expand RIGS into an explicitly defined app to support signals.

RIGS/apps.py

@@ -0,0 +1,8 @@
+from django.apps import AppConfig
+
+
+class RIGSAppConfig(AppConfig):
+    name = 'RIGS'
+
+    def ready(self):
+        import RIGS.signals