Network Graph View

I have put some effort in making a Github-Like network-graph, using the excellent RaphaelJS library. Tested on Firefox, Chrome and IE 10 on my Windows 7 Machine.

- Introduced a new NetworkController (Which is, basically, a copy of the Commit Controller - please do have a look whether one could make that less redundant!)
- Added RaphaelJS Dependency
- Added the JavaScript File for drawing the network graph
- Added some Styles
- Fixed a bug in pretty-format for GIT, see #289 (required)

The thing has been tested on, amongst others, the Linux Core Repo, and it did make a nice figure there, although of course there is lots to improve, still.

![gitlist-screenshot-networkgraph](https://f.cloud.github.com/assets/374658/628190/bdce14b2-d089-11e2-9901-add6f11de7f1.png)