zmq_bus first unit test added. Refactored zmq_bus to shutdown gracefully and to have "targets" for the messages it receives. zmq_bus unit test requires the bus to run in a separate thread. In the init of this threaded object could not find the syntax for super(), using hardcoded call instead. Enabling second test of this unit fails, prolly needs setUp refactor.
Wrapped zmq_bus inside a thread for its unit test. Fixed super issue, it was a syntax error. Fixture has to be class-wide otherwise maybe race conditions between tests and bus daemon. Refactored zmq_bus to have a poller otherwise had an unsolvable lock when bus tried to respond to itself. Added sys.exit when port is occupied.