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

SW-699: adapted ingest to new messaging framework using a central broker with a central exchange and proper routing_keys/queues

SW-699: Use exchange,routing_key syntax for AbstractBusListener constructor, drop use of **kwargs, fix IngestEventHandler as it was still propagating subjects to listen for

SW-699: Make notifications unconfigurable, greatly reducing complexity of the higher abstraction layers.

SW-699: Use a single broker and bus (exchange), and make service names unconfigurable (fixed in Service and RPC). Greatly reduces configuration size.

SW-657: simple priority sorting for new python3 changes, simplified canProduceNextJob method to simple lookup of a single scheduled job

SW-658: replaced SOAPpy by python3 compliant package pysimplesoap. Adapted ingestmomadapter to use pysimplesoap. Added test t_ingestmomadapter to tests soap functionality.

SW-402: merged ltastorageoverview from trunk into LOFAR-Release-3_1 for deployment to production as per request by SOS/SDOS

SW-402: copied srm_url addition to event dict from ltastorageoverview branch into release branch, so yan can use it for an sdc demo

SW-283: pass along the srm_url from the dataproduct notification to the task notification if possible