Update the document target.

The document target makes the documentation, but it is not quite seamless for rolling in to the existing document structure on sourceforge.

The user/ and developer/ directories need their own index.html's, so that links from the geoserver home page work. These should be as simple as adding them to the documents directory and then renaming them and putting them in the right generated/ section.

The other thing is the contrib page. We could move it to another location, but it does sorta make sense with the other developer stuff. The better answer would probably be to include it in cvs, to track changes to it.

Would also be nice to update that page with some nice logos of the contributing organizations.