Git merges in Moodle 2.7.20 by Dan Poltawski

commit aa45fcf78e7d33d7e6ed74a1bd50f9185b7bb77b
Author: Dan Poltawski <dan@moodle.com>
Date:   Sat, 29 Apr 2017 16:01:14 +0800
Tag:    v2.7.20

Merge branch 'MDL-58672_27' of git://github.com/stronk7/moodle into MOODLE_27_STABLE