React 0.5.1
Test JSX + Coffeescript

Thanks to @stillmotion for forcing us to make sure it worked!
Update gemfiles for appraisal testing
Update readme to document coffeescript usage
Add addon config

This makes it possible to use the addons build of React.

Closes #13
Stop storing gemfile.lock files for appraisal

The authors no longer suggest keeping these checked in, so let's stop
doing it.