Gruppo bold doesn't exist, rendering weirdly

@tylerholland 
Not sure how it looks in Windows, but the Gruppo font doesn't render correctly in bold on my mac. I checked Google Web Fonts for a bold alternative but didn't find one. 

I've unbolded the Gruppo headings and tried to compensate by increasing the font-size and letter-spacing. How does this look?

Before:
![screen shot 2014-11-15 at 10 24 33 pm](https://cloud.githubusercontent.com/assets/103781/5057460/518c3222-6d16-11e4-8263-da525c0f65a6.png)

After:
![screen shot 2014-11-15 at 10 24 56 pm](https://cloud.githubusercontent.com/assets/103781/5057461/54f0f894-6d16-11e4-9182-652ed75a10ef.png)