Author: Andrew Davis
MDL-43188 core_message:reimplemented the beep on new message functionality from 1.9
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b0edefb8e5bd6d550b19b6fc748ee6551a0aacef
http://github.com/moodle/moodle/commit/b0edefb8e5bd6d550b19b6fc748ee6551a0aacef
+ 2.5 en [beepnewmessage,core_message]