Add the total for each transaction in the list of transactions

It's a feature we all agreed we needed at HackerBeach 2.

Here's a screen shot:

![screen shot 2014-02-03 at 17 31 15](https://f.cloud.github.com/assets/43297/2066616/380c7ee8-8cf1-11e3-9914-95bd0bc2708b.png)

What do you think? I'm open to suggestions for the layout, this is meant as a discussion starter :)