Finish 1.1.1. Adds nokogiri as a runtime dependency.
Add json dependency to Gemfile for rbx.
Move .gemspec to rdf-microdata.gemspec
Change plugin to extension.
Implement callback modes for #each_statement and #each_triple.
Update reader spec for new rdf-spec reader tests.
Version 1.1.1.1.
Finish 1.1.1.1. Implement callback modes for #each_statement and #each_triple.