Moved last update date to header and size stats columns

The last update date is now in the header on the homepage, with a more clear description:

![Repositioned update date](https://f.cloud.github.com/assets/449006/1982045/03779a38-83ef-11e3-8807-6e37ab267acb.png)

Stats columns are now also a fixed size, and the visit link is subdued/right-aligned.