Author: Andrew Davis
message MDL-24879 added something to cron to remove read notifications
http://git.moodle.org/gw?p=moodle.git;a=commit;h=212badff4dd8610f53ecd1ce908489907e8a043f
http://github.com/moodle/moodle/commit/212badff4dd8610f53ecd1ce908489907e8a043f
+ 2.0 en [configmessagingdeletereadnotificationsdelay,core_admin]
+ 2.0 en [messagingdeletereadnotificationsdelay,core_admin]