@mzikherman: Add "Thumbnail View" section

This is mostly templates + stylesheets filling out layout for the post editing UI. My current plan is to use vanilla Backbone views for the layout but when it comes to the actual section tool + content of the post I'll give [React](http://facebook.github.io/react/) a go for managing state.

![image](https://cloud.githubusercontent.com/assets/555859/4484023/4e8e6838-49b7-11e4-8a33-0335adbd2505.png)

![image](https://cloud.githubusercontent.com/assets/555859/4484031/59b86650-49b7-11e4-833c-462f943f24c3.png)