Author: Andrew Davis
message MDL-24584 2 new strings for messaging UI
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b4dcb6d71107b862f4b4ac4d48c5a4105aee9f50
http://github.com/moodle/moodle/commit/b4dcb6d71107b862f4b4ac4d48c5a4105aee9f50
+ 2.0 en [loggedindescription,core_message]
+ 2.0 en [loggedoffdescription,core_message]