Event Listening

[yasserf]

We want to implement event listening so that we can do the following:

public DeepstreamClient listen( String regex, ListenCallback listenCallback ) {
   ...
   return this;
}

public DeepstreamClient unlisten( String regex, ListenCallback listenCallback ) {
   ...
   return this;
}

// This API will change going on, but only a little
public class ListenCallback() {
   public void onListen( recordName, isSubscribed ) {
   }
}

Be good to use a ported version of:

https://github.com/deepstreamIO/deepstream.io-client-js/blob/master/src/utils/listener.js

[laoluani]

shotgun