Update for coffeescript 1.7

CoffeeScript 1.7 now requires explicit registration of extension:

> 1.7.0 – JANUARY 28, 2014
> When requiring CoffeeScript files in Node you must now explicitly register the compiler. This can be done with require 'coffee-script/register' or CoffeeScript.register(). Also for configuration such as Mocha's, use coffee-script/register.

([source](http://coffeescript.org/#changelog))