Coffee script support is provided by `ember-cli-coffeescript` addon.

This addon provides both blueprints and preprocessor support via a
single `npm install --save-dev ember-cli-coffeescript` command.

https://github.com/kimroen/ember-cli-coffeescript
Merge pull request #1289 from rjackson/remove-coffeescript

Coffee script support is provided by `ember-cli-coffeescript` addon.