Fix NPE when no referrer is set
Merge branch 'master' of https://github.com/datenimperator/rakwik

* 'master' of https://github.com/datenimperator/rakwik:
  Update text to point out Warden integration
  Only perform CI for standard MRI versions
  Bump gem version
  Add Warden detection, improve spec coverage
  Bump version
  Allow jruby to fail
  Emulate decode_www_form for 1.8.7
Bump minor version after bugfix