Initial commercial components

This is a very early attempt at trying to have a framework for commercial components. Design & specs are still in flux, so this is just a first stab at it.

Included here:
- Commercial components as an A/B test for easy testing
- Responsive breakpoints within containers (currently only *.commercial--small* & *.commercial--medium*)
- Very basic styling, pending proper designs

Still to do:
- Handling static assets per component (JS/CSS/Images)


![commercial-masterclasses](https://f.cloud.github.com/assets/518943/1421481/d5bfb840-3fed-11e3-81e2-bf4a0979a881.png)
![commercial-travel](https://f.cloud.github.com/assets/518943/1421482/d5c0e85a-3fed-11e3-8e85-13076f277142.png)