Add empty state panel

I'm not so sure about the graphics anymore. I changed the design quite a bit to match the feeling Helpful currently gives and the style guide, looks fine by me.

![screenshot 2014-01-31 10 52 58](https://f.cloud.github.com/assets/144075/2049294/9dc70cda-8a5d-11e3-87a9-71e99f546e97.png)