Improved favicon

Generated a favicon out of the [logo](http://wiki.bitblueprint.com/skins/common/images/wiki.png) at the [wiki](http://wiki.bitblueprint.com/).

Preview:

![image](https://f.cloud.github.com/assets/1221244/1501368/6b70a8e6-488a-11e3-8cda-d577fb1f5158.png)