Center the header with the content

Before: 
![image](https://cloud.githubusercontent.com/assets/874898/2574417/8dfe197a-b932-11e3-8c74-d0d395e62480.png)
After this PR: 
![image](https://cloud.githubusercontent.com/assets/874898/2574421/9ec56a74-b932-11e3-93c3-46934f2ef2a4.png)