Git merges in Moodle 2.7.18 by AMOS bot

commit 98bb032eadc7a72f7b694b48c122f8326dd9ed52
Author: AMOS bot <amos@moodle.org>
Date:   Thu, 01 Dec 2016 00:06:42 +0800
Tag:    v2.7.18

Merge branch 'MOODLE_27_STABLE' into install_27_STABLE