Add another MailChimp form to the homepage

Matt wants more subscriptions. Here's how Matt wants them.

![screen shot 2013-11-15 at 1 07 30 pm](https://f.cloud.github.com/assets/1829094/1552785/79698ce8-4e29-11e3-91fc-a0b190608ee3.png)

Also change the caps on `Mailing List` to `mailing list!`