- Allow the `/presence/get` endpoint to return multiple channels in a single request (limited to 50)
- When multiple presence channels are initialized in a single Ember runloop, batch them into a single GET request
- Introduce the `presence-pretender` to allow easy testing of PresenceChannel-related features
- Introduce a `use_cache` boolean (default true) on the the server-side PresenceChannel initializer. Useful during testing.