Discussion page style

- Change style of the discussion page
- Remove header bar from application
- Add individual headers to each page

![untitled](https://cloud.githubusercontent.com/assets/4236592/5455850/076350c0-8537-11e4-9804-dcdf0e143955.png) 
The _DiscussionItem_ is used on the discussion index, I agree it´s confusing. What would you suggest?