Add cc:license statements to document as per Wikipedia/dbpedia licensing...

In keeping with the standard practice of declaring copyright and licensing terms in the footer of every web page (since a client can land anywhere), Linked Open Data should declare the licensing terms of the data on each foaf:Document along with the rest of the metadata about that page.  Geonames is a good example of this.

This patch copies in the dual licenses declared by Wikipedia (and dbpedia), CC BY-SA 3.0 and GFDL 1.3.