enhance oai set generation
- support set urn-set-1 for prefix urn:nbn:de:hbz:929:01
- support set urn-set-2 for prefix urn:nbn:de:hbz:929:02
- support set epicur for all objects with urn
- support set open_access for all objects with
AccessScheme=public
- support set aleph for all objects with catalog id