Adds content negotiation support:
 - text/html : Some fancy view
 - text/html : N-Triples
 - text/n3 : N3
 - text/turtle : TURTLE
 - application/x-turtle : TURTLE
 - application/xml : RDF/XML
 - application/rdf+xml : RDF/XML
 - application/rdf+json : RDF/JSON
Merge branch 'enhancement-#3' into develop