Author: Jun Pataleta
MDL-68465 message_email: Add site name to digest email
http://git.moodle.org/gw?p=moodle.git;a=commit;h=1f7e9a698ae6b8d532a33be7b0e99ddf70b56fbe
http://github.com/moodle/moodle/commit/1f7e9a698ae6b8d532a33be7b0e99ddf70b56fbe
+ 3.9 en [messagedigestemailsubject,message_email]