Mobile Friendly Redesign

Removed unused assets from H5BP, added new stylesheets, and made it friendly to mobile devices. Also added a section that briefly reviews the DSL. There's a couple images still in the `img` folder that might be removable, and it would be nice to have a Retina-friendly version of `img/artoo.png`. Please let me know if you think anything's missing or incomplete.


You can find a live version [here](http://share.andrew-stewart.ca/artoo/index.html).