Mocha.js Engine Support

Refactored the way engines are handled and rebuilt the Mocha Engine. 

This branch lets you run mocha.js tests without having the cross browser origin issues that come with linking directly to ```raw.github.com```. Instead I leverage the fact that chai.js and mocha.js are required modules, and include the code via the ```node_modules``` directory.

I had to refactor how engines export seed and test runner data as well. Instead of reading the entire file, I wrapped the exportable code in a closure and export it. This gives you flexibility to do more processing and curating of any engine code.

We really should think about using [browserify](https://github.com/substack/node-browserify) for the engine code. It would greatly simplify the program logic itself.