Added user-badges component

I'm going to use this component in hero banners and also in the new flickr widget, so I think that may worth convert this tiny html into a component...

Also, we can extend it to be used in community. 
![screen shot 2014-06-20 at 11 39 31](https://cloud.githubusercontent.com/assets/1152640/3338749/347ccd52-f860-11e3-95c9-07ad04fe4fb7.png)

Maybe we could use `theme--` prefixed classes here? Like https://github.com/lonelyplanet/rizzo/blob/master/app/assets/stylesheets/core/core_components/_faux_inputs.sass#L25

so it would be `<div class="user-badge__source theme--dark"> ... </div>`