Author: Mark Nelson
MDL-61255 core_message: add warning when notifications not migrated
http://git.moodle.org/gw?p=moodle.git;a=commit;h=23de6f3a2d351da44d08e1c8369a764711928126
http://github.com/moodle/moodle/commit/23de6f3a2d351da44d08e1c8369a764711928126
+ 3.5 en [notificationdatahasnotbeenmigrated,core_message]