Add navigation element mockup

The following navigation elements are to be added between main selection controls and treemap:

![screen shot 2014-07-02 at 11 29 33](https://cloud.githubusercontent.com/assets/78356/3454031/caf9d972-01cb-11e4-8bdd-f6bd15b7d89e.png)

This navigation needs to be updated when main controls change and when navigation inside the treemap occurs.