Style downloads.jboss.org and docs.jboss.org to reflect the JBoss Community theme

When we eventually switch on directory listings for http://downloads.jboss.org and http://docs.jboss.org we should replace the default L&F with something based on our style. Currently both http://downloads.jboss.org and http://docs.jboss.org go to the project matrix but it's possible to navigate subdirectories of docs.jboss.org:

http://docs.jboss.org/docbook/