New version of button group. Selectable.

![image](https://cloud.githubusercontent.com/assets/2095625/3750982/012fc4da-17fb-11e4-83c2-97f04a9ac58f.png)

![image](https://cloud.githubusercontent.com/assets/2095625/3751073/da7182b0-17fb-11e4-8c0f-3db0e179a465.png)