Use Yarp to Speed Up Build Process

Yarp is a gem cache proxy thingy for rubygems.org

https://github.com/mezis/yarp

It's amazing:

![screen shot 2014-01-24 at 9 33 34 pm](https://f.cloud.github.com/assets/237985/2000761/3556175c-8569-11e3-9f69-26c09631b50b.png)