Git commits in Moodle 2.7.19 by Marina Glancy

commit b34eca2f9eb10c3d8519c9068fe40863de3f3bf1
Author: Marina Glancy <marina@moodle.com>
Date:   Sat, 04 Mar 2017 12:22:12 +0800
Tag:    v2.7.19

MDL-58010 user: allow to update only whitelisted preferences