ADD: rdf basic serialization for social network
ADD: most basic rdf API ever
FIX: use respond to with rdf
ADD: types to elements in rdf api
FIX: update rake gem
ADD: custom serializer class
ADD: prefixes to basic rdf api
ADD: basic version of the SN vocabulary
Merge pull request #10 from fespinoza/basic_rdf_api

Basic rdf api, closes #2