Add relator fields, set title to text_long

All fields without an RDF mapping defined in [1] are omitted for now,
the multiple occurences of dct:contributor all map to
field_edoweb_contributor.

Please run update script

Fixes EDOZWO-323

[1] https://wiki1.hbz-nrw.de/pages/viewpage.action?pageId=3900729
Display related fields as drop-down list

Fixes EDOZWO-300