Host CommonJS JavaScript environments in Ruby via MiniRacer

This gem was ported from commonjs.rb

The internet is now awash with non-browser JavaScript code. Much of this code conforms to some simple conventions that let you use it anywhere you have a JavaScript interpreter available. These conventions are collectively called "commonjs"

The MiniRacer interpreter allows us to evaluate JavaScript. Therefore, why shouldn't we be able to use commonjs applications and libraries?

CommonJS::MiniRacerEnv passes all of the Modules 1.0 unit tests.

env = CommonJS::MiniRacerEnv.new(mini_racer_context, path: '/path/to/lib/dir')
env.runtime.eval(%q|var foo = require('foo.js')|)

By default, all you get with a bare commonjs environment is the Modules API

The plan however, is to allow you to extend your commonjs environment to have whatever native interfaces you want in it. So for example, if you want to allow filesystem access, as well as access to the process information, you would say:

env.modules :filesystem, :process

Only MiniRacer is supported.