Git commits in Moodle 3.7.0 by Matt Porritt

commit 2cd901a4e7bcf24d053f161d806fb9f4a4e978d3
Author: Matt Porritt <mattp@catalyst-au.net>
Date:   Thu, 20 Dec 2018 12:32:46 +0800
Tag:    v3.7.0-beta

MDL-28505  Backup: Asynchronous backup and restore