SW-827: check in messagebus and rpc/service tests if the TemporaryExchange/TemporaryQueue's are really deleted. Some tests fail now, proving bug SW-827 exists.

SW-811: ToBus.send now retries to reconnect and resend the message upon connection loss. Added test for that as well.

SW-811: added test to prove that sending a message on a broken connection fails with a MessagingError

SW-699: raise in BusListener when it is detected that the provided handler is an empty template handler

SW-699: added UsingToBusMixin, and (re)use that in all the ServiceMessageHandlers and some AbstractMessageHandler derivatives

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