Updated sidebar to expand to show clicked subtopics, and no sliding.

Here's what I came up with so far, @66eli77, @jtamiace, @rtibbles.
Commenting this out breaks nav. Please fix.
End up with urls like this: 
![image](https://cloud.githubusercontent.com/assets/1680573/4722876/f1d9143a-5942-11e4-8220-5e87b1a49f45.png)