Git commits in Moodle 2.7.20 by David Monllao

commit d463c79ec252b18bf8b95cc3f52b9f978f5e47a1
Author: David Monllao <davidm@moodle.com>
Date:   Wed, 03 May 2017 10:27:36 +0800
Tag:    v2.7.20

weekly release 2.7.19+