Git merges in Moodle 3.2.4 by AMOS bot

commit aac5a4f1035c88500bf1f8c56761cc9e22e7164e
Author: AMOS bot <amos@moodle.org>
Date:   Sat, 24 Jun 2017 00:09:03 +0800
Tag:    v3.2.4

Merge branch 'MOODLE_32_STABLE' into install_32_STABLE