Flattr in Sidebar

There's another Haml trick here if I'm not mistaken:

```haml
%a.FlattrButton{data: { flattr: { button: "compact", category: "text", tags: "events, calendar, hacking, hackers", uid: "bodo.tasche"}}, href: "http://hacken.in", style: "display:none;", title: "hacken.in"}
```