Rationalize layout

Switches us to a percentage-based layout. Removes a lot of resolution-dependent edge cases. Also expands the map in the deep dive to fill the whole right column:

![screen shot 2014-11-02 at 10 18 05 am](https://cloud.githubusercontent.com/assets/86435/4875712/3087ed36-62a4-11e4-93ce-829fe8a6c09c.png)

Can we use the `transitionend` event instead? (https://developer.mozilla.org/en-US/docs/Web/Events/transitionend) We should be able to attach a single event listener to the `transitionend` event of `this.$('.b')`, and then the map size invalidation should get called both for growing and shrinking columns.