Add lv:rpbSubject.
Add lv:rpbSubject.

See https://github.com/hbz/lobid/issues/298#issuecomment-214668052

jschnasse/regal-api,jschnasse/regal-api,hbz/lobid-rdf-to-json,jschnasse/regal-api,jschnasse/regal-api,edoweb/regal-api,edoweb/regal-api,edoweb/regal-api,edoweb/regal-api