Git commits in Moodle 3.5.0 by Ngo Nghia

commit 5a8d683fb2403876e0b22b89ad7636f1ee8cdc4f
Author: Ngo Nghia <ngonghiahp93@gmail.com>
Date:   Tue, 20 Dec 2016 08:44:17 +0800
Tag:    v3.5.0-beta

MDL-25617 backup: backup/restore using extra_question_fields