Master detail

Adds master detail flow for devices with xlarge screens (width > 600dp). 

This is my first real experience with this kind of wizardry, so please look out for rookie mistakes.

![screenshot_2014-05-05-00-04-50](https://cloud.githubusercontent.com/assets/1841551/2874140/4b81bfdc-d3d8-11e3-8eb8-097066b4b956.jpg)