Git commits in Moodle 3.5.2 by Claude Vervoort

commit c46c85055b4f7cc5b4ad3549dadea8833b17533c
Author: Claude Vervoort <claude.vervoort@cengage.com>
Date:   Thu, 26 Jul 2018 23:20:04 +0800
Tag:    v3.5.2

MDL-62993 ltiservice_memberships: make message an array per spec