Starting and Stopping an Event Bus
Starting and stopping an event bus is simple.  Just create one and it's started.  To stop a bus, call its shutdown() method and it terminates gracefully, allowing queued
 events up to 30 seconds to be delivered. 
You can change the shutdown timeout by calling EventBus.setShutdownTimeout(long).  Once the timeout expires, the bus is forcibly terminated and no more
events will be delivered.

