Author: Mark Nelson
MDL-40913 core_message: replaced 'block contact' add_to_log call with an event
http://git.moodle.org/gw?p=moodle.git;a=commit;h=3f3d9521de976dc224950606ab4830652bbf512e
http://github.com/moodle/moodle/commit/3f3d9521de976dc224950606ab4830652bbf512e
+ 2.7 en [eventmessagecontactblocked,core_message]