Cleaned up read_url
It's now a simple wrapper around the get request made with rest
Ported grader.js to CoffeeScript
Left todo :
  - Find a way to add #!/usr/bin/env node
    to the compilation process, but out of the englobing (function () {}())
  - Implement the server in CoffeeScript
  - Test the API call
  - Check out Iced CoffeeScript to manage the sync and async part.