[READY] Load minified CSS and JS on live env, unminified on sandbox env

Detects whether current environment is either sandbox or live.
- If sandbox, unminified CSS and JS are loaded (`/css/styles.css` & `/js/*.js`)
- If live, minified CSS and JS are loaded (`/build/styles.min.css` & `/build/scripts.min.js`)

Also removed the `build/` and `css/` directories from being committed to Github. This will help to keep commits clean.

![Sandbox](http://i4.photobucket.com/albums/y133/mikexchecka/1186352942922.gif)