Added widget section and flickr widget in styleguide

Say hello to our new "Widgets" section in the styleguide! 

The first one: Flickr widget. Uses image cards as main component to render the photos. 

![screen shot 2014-06-26 at 12 00 22](https://cloud.githubusercontent.com/assets/1152640/3397111/c5195044-fd18-11e3-9ca3-544d1979f6ba.png)

Yeah, I know... but this is the only way that I can do this now... may be some ruby guy should review and refactor it... Do you think that this should be in waldorf instead of in rizzo? (that is what I'm thinking)