Add labels to linked objects

[acka47]

For example instead of:

{
   "id":"http://w3id.org/class/hochschulkompass/S349#",
   "type":"Concept",
   "broader":{
      "id":"http://w3id.org/class/hochschulkompass/B348#"
   },
   "inScheme":{
      "id":"http://w3id.org/class/hochschulkompass/scheme#"
   }
}

it should be:

{
   "id":"http://w3id.org/class/hochschulkompass/S349#",
   "type":"Concept",
   "broader":{
      "id":"http://w3id.org/class/hochschulkompass/B348#",
      "prefLabel":{
         "de":"Philosophie"
      }
   },
   "inScheme":{
      "id":"http://w3id.org/class/hochschulkompass/scheme#",
      "title":{
         "de":"Fächersystematik Hochschulbildung in Deutschland"
      }
   }
}