Fix Buttons 'skip' and 'next' in the end of the tutorial

Hello guys, yesterday I was trying the tutorial and the batman.js is awesome. However I found a bug where the buttons `skip` and `hasNext` are visible in the end.

@nickjs

Screenshots:

Skip Button
![screen shot 2013-09-05 at 10 11 13 am](https://f.cloud.github.com/assets/410080/1088173/e847402c-162c-11e3-94c8-4b078d5de41c.png)

Next Button
![screen shot 2013-09-05 at 10 11 23 am](https://f.cloud.github.com/assets/410080/1088174/f27827e6-162c-11e3-9c75-f9f577735625.png)