Git commits in Moodle 3.6.2 by Claude Vervoort

commit 8d84ee97dafc8ff78cf8487fc8a0e17772022bff
Author: Claude Vervoort <claude.vervoort@cengage.com>
Date:   Mon, 10 Dec 2018 23:26:12 +0800
Tag:    v3.6.2

MDL-64357 ltiservice_gradebookservices: fix cleanup deleting lineitems