Make ServiceProvider to no longer extend from EventEmitter

[joshuamarquez]

I believe that extending from EventEmitter in ServiceProvider might not be necessary if we implement callbacks for communication between ServiceEmitter + ServiceProvider + CustomProvider. Using callbacks would be a cleaner and better implementation of ServiceProvider since ServiceEmitter is also extending from EventEmitter.

How so? well what if instead of listening wantsData event in some custom emitter we just override a method from ServiceProvider maybe called with the same name of the event (onWantsData())? the same could happen for data and error events used in ServiceEmitter.