Git commits in Moodle 2.7.13 by Cameron Ball

commit 9f91c23536a31ba2dc91b0ba2ae726b1757a20cb
Author: Cameron Ball <cameron@moodle.com>
Date:   Thu, 11 Feb 2016 11:25:53 +0800
Tag:    v2.7.13

MDL-52651 htmlpurifier: Append rel=noreferrer to links.