Allow for end-to-end testing offline(without kafka locally)

[sidmitra]

For eg dummy broker can call receiver methods with the event class instead of printing.
There's a gap in being able to test pipeline end-to-end by calling bus.send(myevent) and checking if consumer got it.

There might need to be a way to specify a list of specific consumer that i want to run, instead of all in a sequential list.