Update 5-forms.md

Updated form tabs example so the styles look nicer. I was originally going to create a bug to fix some visual design issues, which I will still due. But this looks ok:

![screen shot 2014-11-04 at 4 51 09 pm](https://cloud.githubusercontent.com/assets/1386966/4910968/96dddf94-6486-11e4-8346-b45424e96bb4.png)