Adding pause/go button.

Images:
 * ![image](https://f.cloud.github.com/assets/21212/803246/01e2ddae-edea-11e2-93b0-0cbca2ce6923.png)
 * ![image](https://f.cloud.github.com/assets/21212/803247/08963a9c-edea-11e2-8f3f-94c765a51ac4.png)