Feature/responsive tables

Inspired by: http://jonathanstark.com/labs/double-zebra-responsive-tables/

Prompted by: https://basecamp.com/1730484/projects/1304-wayne-edu-redesign/messages/21395287-responsive-tables#comment_129274959

Demo: https://www.dropbox.com/s/fzk3exkq86fc8rb/responsive-tables.mov

Screenshots:

![screen shot 2014-04-21 at 8 57 53 pm](https://cloud.githubusercontent.com/assets/37359/2760518/4f0bd4ae-c9b9-11e3-8951-73ab97ac8d31.png)

![screen shot 2014-04-21 at 8 58 00 pm](https://cloud.githubusercontent.com/assets/37359/2760519/5269c700-c9b9-11e3-8124-1c797413913f.png)