Show Commit Diff in every node-Body (fix for #32)

It's not ready yet I think, but I wanted to show it to you now.

I use the FileViewModel, which makes it a bit ugly, but saved a lot of code :grin: 

As mentioned in the feature-request, there is something that makes it ultra slow.
![Imgur](http://i.imgur.com/3iKIz1M.png)

If there is no way around:
- You could load (and cache) the diff on request (when you click on the file-name)
- You could load every diff at the beginning and only parse it, when requested (I think the parsing is what takes so long)

What do you say..?