Yellow tint-color?

I tried using the yellow color from the JavaZone-logo as the global tint color, as well as for the headings. We use that color quite a lot in other JavaZone things. I also made the profile pictures round (instead of round-rect) to match the web page. 

Personally, I think it looks nice, but I'll let you decide if you want to merge it or not :)

![iphone](https://cloud.githubusercontent.com/assets/505752/3942149/145fcb4a-2557-11e4-94aa-61b75e92b906.png)

![ipad](https://cloud.githubusercontent.com/assets/505752/3942150/19da52f2-2557-11e4-8c5c-8a7dd8030a5a.png)