Rearrange sidenav so that the user can navigate via tab more easily

Before:

![before](https://cloud.githubusercontent.com/assets/3824954/3407699/513fc0c6-fdb4-11e3-9c9c-64d2581ac665.gif)

After:

![after](https://cloud.githubusercontent.com/assets/3824954/3407708/8a756cf6-fdb4-11e3-8a9a-c90074311033.gif)