Using Cloudinary / Attachinary

Anyone here used Cloudinary & Attachinary? Cloudinary is a Heroku plugin for storing images and Attachinary is a gem for handling attachments that is Cloudinary-aware. I’ve gone through all the installation instructions, yet get the following error when starting my rails (V3.2.14, ruby 2.0) app:

cannot load such file -- coffee_script
  (in /home/jseidel/.rvm/gems/ruby-2.0.0-p247/gems/attachinary-1.2.6/lib/assets/javascripts/

Any suggestions?

Edit. I was able to get this working by adding:

  s.add_dependency 'coffee-rails'

to attachinary’s gemspec.

What’s that all about? I thought the Gemspec would take care of things like that.