Convert website to Bootstrap, give it a navigation bar, make it mobile-friendly

Desktop screenshot: ![website_screenshot_1](https://cloud.githubusercontent.com/assets/4154884/4200594/611c8a94-3813-11e4-84a5-1d0bcc80fdfc.png)

Mobile screenshot: ![screenshot_website_2](https://cloud.githubusercontent.com/assets/4154884/4200601/6b77b8e2-3813-11e4-8856-1a32e8794c11.png)