Bower support

Notes
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- Helps with #197 (but you'll still have to [register your package](http://bower.io/docs/creating-packages/#register)).
- You might want to change the keywords.
- normalize.css and Raleway are included in `index.html`, but aren't part dependencies of the Bower package. You might want to add `css/normalize.css` to the `main` field or add normalize.css as a dependency if you want people to always use normalize with Skeleton (you'll still need to remind users to include the CSS file though). Also, you might want to add a note that people can get Raleway from Google Fonts.