Refactor Client-Side JavaScript

Much of the client JS has become unruly, [static.js](https://github.com/donejs/bit-docs-donejs-theme/blob/master/static/static.js) for example, is a pile of spaghetti heavily spiced with jQuery.

__I propose the following changes__:
- Refactor all of `/static/static.js`.
- Modularize/Organize into components.
- Use CanJS instead of jQuery where possible.
- Consider using Bootstrap's scroll spy plugin.
- Remove plugins from `/static/js`
- Replace with NPM modules
- Consider rewriting them with CanJS
- Remove most or all of the JS for responsive stuff. Everything I have seen so far could be done with pure CSS.
- Write tests for as much of the client code as is reasonable.