Failed payment helper

This adds messages and pre-written emails to help assist potential campaign contributors when they run into a payment failure.

Specifically, this provides messages for payments that fail @ tokenization as well as payments that return declines from the Crowdtilt API.

![screen shot 2013-11-21 at 3 38 17 pm](https://f.cloud.github.com/assets/1132438/1597039/6c210fde-5306-11e3-9cb1-e5772397d54a.png)