[EDC - JSON-LD context] remove dc:Identifier, update to adms:Identifier

[Esayos]

term "identifier" at json-ld context (

European-Learning-Model/rdf/ap/edc/edc-ap-context.jsonld

Line 404 in 3a3348b

"identifier": {

) should point to adms:Identifier instead of dc:Identifier (dc:identifier is not used anymore).

Also, term admsIdentifier (

European-Learning-Model/rdf/ap/edc/edc-ap-context.jsonld

Line 79 in 3a3348b

"admsIdentifier": {

) is not used anymore in json-ld serialization and can be removed from the context