Return Invoices

Rebase and squash of 2-2-dev on top of 2-2-stable.  Only additional thing 2-2-dev has returns & exchanges stuff that isn't in 2-2-stable.

We were getting too many colors of the rainbow in our git history :)

![screenshot-2014-10-03-09-28-20](https://cloud.githubusercontent.com/assets/23050/4508362/109dbdb2-4b15-11e4-86cb-65e629fa5b42.png)