Git commits in Moodle 3.5.4 by Amaia Anabitarte

commit ecb4b0260e61110af011a7040a8b9c2f1112fb80
Author: Amaia Anabitarte <amaia@moodle.com>
Date:   Wed, 19 Dec 2018 18:40:16 +0800
Tag:    v3.5.4

MDL-64400 core_messages: Mark notifications sent via email as read


commit da73f1364db2dcc0ee0d15b7350cbbbcf6223f12
Author: Amaia Anabitarte <amaia@moodle.com>
Date:   Fri, 14 Dec 2018 23:14:32 +0800
Tag:    v3.5.4

MDL-64400 core_messages: Allow cron to delete unread notifications too


commit f91e884d689571207a3ee3ec9a45e6ca5731d809
Author: Amaia Anabitarte <amaia@moodle.com>
Date:   Wed, 12 Dec 2018 02:06:52 +0800
Tag:    v3.5.4

MDL-60518 core_competency: Set $USER global variable for tests