Order Chapter page

Hello everyone,

right now the chapters page is a little overwhelming (thanks to the good progress of Nodeschool :+1: ).

I just sorted them by regions a bit:

![nodeschool_io](https://cloud.githubusercontent.com/assets/841788/4593121/3df1706a-5083-11e4-8e5d-44391c5d9dba.png)

Best,
Finn