The callbacks are stored by their id in the RPCServer so they are properly uniqued. This prevents the same callback from being added multiple times as a change listener.
All realm operations for the RPC are now done in their own thread so it can be allowed to block on waiting for callback results. The recursive and multi-threaded nature of this makes it pretty tricky, but it works!
It still only tries localhost for the simulator, but for devices, we now get a list of possible IP addresses to attempt to connect to before throw a more helpful exception.
Resolves#284 and fixes#276
Scott Kyle