Added RDF::PremisEventType to config and generated vocab - replaces RDF::Preservation::EventType.
Rake tasks updated to include full class name in descriptions
README updated with a little better description and list of vocabs

Removed RDF::Preservation module - EventType class moved to RDF::PremisEventType
RDF::PREMIS moved to RDF::PREMIS::V1
All vocabularies now loaded when "rdf-vocab" is required