v1.1.3 (Fixes Binding to channel events cancels calls to onConnectionStateChange)

Whenever onConnectionStateChange is set, then any bind calls for events would cause the onConnectionStateChange to stop working. This was caused by the PusherClient class and the Channel class both listening to separate instances of the event channel stream and the bind call would override the initial listener set by PusherClient. To fix this, a StreamHandler contract was added to allow multiple classes to register their listeners and all get access to the same event channel stream.