PROV-962 Generic refinery relationships

This is a new PR which now creates a 'relationships' setting on splitter and hierarchyBuilder refineries. This means you can import related things on related things (on related things ....)
This is a fleshing out of http://clangers.collectiveaccess.org/jira/browse/PROV-962.

The Unit tests do fail, but that is unrelated to this PR and those tests are fixed in #125