Support `nwbibspatial` and `nwbibsubject` queries and facets

See https://github.com/hbz/nwbib/issues/54

Deployed to staging. See:

- http://test.lobid.org/resource?format=full&nwbibsubject=http://purl.org/lobid/nwbib%23s102060
- http://test.lobid.org/resource?format=full&nwbibspatial=http://purl.org/lobid/nwbib-spatial%23n16
- http://test.lobid.org/resource/facets?field=@graph.@type&nwbibsubject=http://purl.org/lobid/nwbib%23s102060
- http://test.lobid.org/resource/facets?field=@graph.@type&nwbibspatial=http://purl.org/lobid/nwbib-spatial%23n16