Really 64

- SubscriptionManager
- SubscribeAggregator
- ObjectSubscriber
- Replayer
- GorillaCenter new subsxription handling
- All the Gorilla wiring
- JSON parsing fix
- WIP of Unsubscribe handling
I think we aren't going to need that in the future and for the API consistency. I can discuss that with @AhmedSoliman again. you can't use one replayer to replay collection events and object events. In the future you will need two types of replayers. One will replay only `created` events and another one for object events (update and delete). So don't write code that you aren't sure that you will need that.