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

This includes:
- python executable -> python3
- Help texts
- #! specifications
- Shell scripts

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

SW-283: processed review: factored out insert_missing_directory_tree_if_needed from one method in ingesteventhandler to multiple reusable methods in LTAStorageDb

SW-283: start IngestEventHandler with configurable and proper default options in scraper, so that the scraper will automatically visit the recent additions from ingest.