Port to Bootstrap framework and other related tweaks

Pretty big changes on the back end if not the front. A quick run down:

Rewrote index.html. Rewrote half of main.css. Modified font-weights for readability on mobile and tablet (left the italics to create some separation and it looks fine). Remade in Illustrator the Assembly icon you were rightly commended for, just to even up the curves.

Note that I somehow ended up adding the config.yml and Rakefile from my local directory. I didn't do that on previous commits so might want to check it didn't screw anything up in your configuration.