Remove the rdf_types since we're now specifying the RDF vocabularies in the rdf directory.
Rename the Nyucore model to NyuCoreRdfResource and have it read from the nyucore gem for its metadata. Add a spec for the model.
CamelCase NyuCoreRdfMetadata
Change the name of the NyuCoreRdf model and its spec
Remove unused nyucore metadata datastream.