Micro-challenge: Virtual Attributes

@mikelikesbikes, @ryanbriones

![form_ui](https://f.cloud.github.com/assets/3526141/1625094/08452ebc-56cd-11e3-8998-2e55c9bf88d8.png)
![form_code](https://f.cloud.github.com/assets/3526141/1625095/0845f27a-56cd-11e3-88dc-a3ca818be9c4.png)