Add bower deps instead of built in deps

Wanted to get slightly more familiar with bower so using this as a starting point.

Replaced the `lib` directory with a `bower.json` file. `bower install` is run with local bower copy as an npm `postinstall` hook. Seems saner than maintaining a lib directory.

Had to update travis config to use node 0.10 vs 0.6, ran into a bower issue there with build.

I'm pretty sold on this approach. @kpdecker any objections?