Author: Mark Nelson
MDL-36941 core: added events for notifications
http://git.moodle.org/gw?p=moodle.git;a=commit;h=376a79c242399aa5fce2c17cf547579b83c8ef47
http://github.com/moodle/moodle/commit/376a79c242399aa5fce2c17cf547579b83c8ef47
+ 3.5 en [eventnotificationviewed,core_message]
+ 3.5 en [eventnotificationsent,core_message]