Further reduce dependency on external libraries

While this might not be what you are after, I have made baron less dependent on external dom and event libraries (e.g. prefer browser native methods/interfaces, and fallback to smaller polyfill if not available).

There are a few changes:

- replace $ with querySelectorAll and add/removeEventListener

- add/removeClass with elem.classList.add/remove

- modify css attributes directly with elem.style.property

- added classList, EventListener polyfill so the example works in IE8+

PS: I love the idea of this script, may I know if it's licensed under MIT so I can make use of it?