SW-699: do not use direct_address anymore. only send messages to the exchange with a proper routing_key

SW-699: fixed doctest. added check for ack/reject lofar message. reuse current queue connection when getting nr_of_messages_in_queue.

SW-699: added documentation to RPCClientContextManagerMixin. renamed rpc_service.py module tp rpc.py, and it's classes to RPCClient and RPCService. Moved Request and ReplyMessage into rpc.py module. Mader MessageFactory and used it in FromBus and rpc.py

SW-699: specify the kwargs not in the contructor, or else you might lose some of the kwargs which are already normal arguments like subject, priority etc

this tool is only meant for live listening, not for historic logs

SW-699: adapted OTDBBusListener to new messaging framework. Users should now implement a OTDBEventMessageHandler subclass with onObservation<Event> methods.