some cleanup needed

[mpo-vliz]

• change project name and ldes-consumer prefix away from 'kgap' to something 'bodc, ldes, nerc, ...' (see aphia-ldes-sync for inspiration)
• document using env vars to control memory of GDB in case people want to run this on laptop
• switch using ldes2sparql from maregraph-eu (not rdf-connect)
• include better tests to compare ingest with live sparql endpoint
• ...