Vanchi/bring back notifications while syncing

- Bring parity between old and new server for sync v1/v2.
- Sync expects notifications to arrive, so send them
- V1 is broken just the same as old server
- Make v2 primary for testing sync
- Make tests ignore order of delivery from redis (hash order is random)

/cc @zendesk/zendesk-radar

### Steps to merge
 - [ ] :+1: of the team

### References
 - Jira link: 
https://github.com/zendesk/radar_client/pull/36

### Risks
 - Presence may behave differently than expected.