Git commits in Moodle 3.3.4 by Brendan Heywood

commit f93839e2ca0f3cea38aed034f0f262e1711c0a2c
Author: Brendan Heywood <brendan@catalyst-au.net>
Date:   Tue, 05 Dec 2017 14:05:47 +0800
Tag:    v3.3.4

MDL-60968 auth: Allow more flexibility with mapping attributes