Author: Mark Nelson
MDL-40913 core_message: replaced 'add contact' add_to_log call with an event
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0d9bdf6185794a86049016f8d183a2c1f171fb27
http://github.com/moodle/moodle/commit/0d9bdf6185794a86049016f8d183a2c1f171fb27
+ 2.7 en [eventmessagecontactadded,core_message]