introduces  skos:prefLable to add display info for lod resources
- lod resources are introduced as nested objects
- for known creator, contributor and subject
- e.g.
  "subject": [
    {
        "prefLabel": "Soziale Probleme und Sozialdienste; Verbände",
        "@id": "http://dewey.info/class/360/"
    },
    {
        "prefLabel": "Freizeitgestaltung, darstellende Künste, Sport",
        "@id": "http://dewey.info/class/790/"
    }

],