Git commits in Moodle 2.2.5 by Andrew Robert Nicols

commit 6bec1fe66f5dd09dfdcccd5ba110383ed0c6c4a5
Author: Andrew Robert Nicols <andrew.nicols@luns.net.uk>
Date:   Fri, 13 Jul 2012 22:01:37 +0800
Tag:    v2.2.5

MDL-34322 Don't display empty navigation nodes which have no link