Add Feedback link

![image](https://cloud.githubusercontent.com/assets/1192780/4194043/791602da-37a8-11e4-9c97-2ece8d5008f8.png)

Add feedback link so users can easily vote on and suggest new features.

Can we name it 'Feature request tracker' or 'Feature requests'?
This will make it much clearer what it is for an prevent people posting bugs and questions on there (which we have to delete manually).