JSONLD: Relational attributes are not defined in @ context

[DavidLeoni]

here for Production area entity ids are in the value field, but they should use a jsonld tag like "@id":"http://SERVER_URL/2089", or we can keep the number but specify the server path in the @context.

Also, "operator": "EQUAL", is redundant.

{
        "conceptId": 120792,
        "Production area": [{
            "creationDate": 1425489390514,
            "modificationDate": 1425489390514,
            "dataType": "STRING",
            "operator": "EQUAL",
            "value": "2089"
        },
        {
            "creationDate": 1425489390515,
            "modificationDate": 1425489390515,
            "dataType": "STRING",
            "operator": "EQUAL",
            "value": "1831"
        },