Commercial option interstitial

This creates an optional interstitial page, broken down by commercial and non-commercial customers

Screenshots!

Commercial:
![image](https://cloud.githubusercontent.com/assets/750477/4451867/19df911e-483d-11e4-820c-75cdf722369a.png)

Non-Commercial:
![image](https://cloud.githubusercontent.com/assets/750477/4451873/2b23eba0-483d-11e4-941b-01ce4d5898ac.png)

Hey am I dumb or does this not work? I don't see :author or :language on the group model.