Update index.js to work with coffee script > 1.7.0

Hey, I don't know much about coffeescript but I had to make this change to be able to use it - according to [this](http://stackoverflow.com/questions/4768748/requireing-a-coffeescript-file-from-a-javascript-file-or-repl) stack overflow entry this change is required post coffee 1.7.0.