Ticket #17: Add RDF.rb to bundle.
Register RDF N-Triples MIME type.
Add Contribution#to_ntriples method to render contribution as RDF N-Triples.
Respond to requests for contribution records in RDF N-Triples format.
Add method to construct RDF graph for contributions.
Ticket #17: Add RDF vocabulary for EDM.
Add more DC properties to contribution RDF graph.
Ticket #17: Add EDM classes to RDF vocabulary.
Ticket #17: Add RDF vocab for ORE.
Ticket #17: Model contribution in RDF as ore:Aggregation of edm:ProvidedCHO and edm:WebResource.