0.4.0

• Allow dumping a single conceptscheme to RDF. This does not dump the entire
  conceptscheme with all it's concepts or collections, just information on the
  conceptscheme itself and it's top concepts.
• Allow dumping a single concept or collection to RDF, and not just an entire
  conceptscheme with all concepts or collections.
• Add skos:inScheme information to RDF dumps.
• Better handling of dc(t):identifier. When reading an RDF file both
  dcterms:identifier and dc:identifier are considered when analysing the
  identifier. During dumping, we also dump to dcterms:identifier.