Use some default icons for seantis.dirbase/contacts content types.

I reused already existing icons from the iconset. 
We can implement new ones later. 

Directory:
![screen shot 2014-11-26 at 11 30 10](https://cloud.githubusercontent.com/assets/437933/5199781/9c19e040-755f-11e4-819a-46dbde923637.png)

Directory item:
![screen shot 2014-11-26 at 11 30 42](https://cloud.githubusercontent.com/assets/437933/5199788/b14d97e0-755f-11e4-82b4-5f086efd1aa7.png)

Directory item contact:
![screen shot 2014-11-26 at 11 31 17](https://cloud.githubusercontent.com/assets/437933/5199792/c4cf3a76-755f-11e4-93b5-d4761b1231bd.png)

In the last case, there's a CSS bug, which adds a margin(left/bottom) to every `ul`on the page. I guess this was not the intention. I fixed this in the second commit.  

`.seantis-directory-item` is a class on the body and I guess the change should only affect the `#content` part of the site.