Changes for operator signoffs:

- auth middleware to add/remove user to/from control room group based on IP.
- new model for operator signoffs (event, instrument unique_together)
- form to create, edit, and delete the operator signoff object
- eventlog messages for changes to signoff objects.
- OperatorSignoff serializer and LVAlert message
- alert operator of outstanding events on landing page.
- new labels and migration
- Added logic to create/remove H1OK, H1NO, etc. labels.
- Exposing the OperatorSignoff List resource through REST interface (GET only).