Git merges in Moodle 3.1.11 by David Monllao

commit f9000970ca745272562540380a72425e6fdb89fc
Author: David Monllao <davidm@moodle.com>
Date:   Thu, 01 Feb 2018 21:26:53 +0800
Tag:    v3.1.11

Merge branch 'install_31_STABLE' of https://git.in.moodle.com/amosbot/moodle-install into MOODLE_31_STABLE