make rows hold floated contents

After `/`, `/examples.html` is the most visited page on batmanjs.org. I'd like to put some beautiful batman.js code right in front of their faces:

![image](https://cloud.githubusercontent.com/assets/2231765/3708835/1c6340b0-144a-11e4-9676-8b53d7abd310.png)

Also, I've updated the example listing.