User API keys

This PR adds the ability to manage user's API keys.
The UI design is far from being good, but I think we can review that later.

![image](https://cloud.githubusercontent.com/assets/43977/5425702/012e00fc-8301-11e4-9fa2-7818ce83dec0.png)

![image](https://cloud.githubusercontent.com/assets/43977/5425703/12121ce6-8301-11e4-9823-cf80bd489a43.png)

![image](https://cloud.githubusercontent.com/assets/43977/5425705/227eb1d4-8301-11e4-9e6b-93df6d75f665.png)