Add register module

[kutu]

to be able to do

data = require 'data.cson'

I was looking into https://github.com/JavascriptIsMagic/require-cson/blob/master/register.js
And then I took a look at https://nodejs.org/api/modules.html#modules_require_extensions
And it says Module.extensions is deprecated, and there is better way to do it.