Author: Mark Nelson
MDL-29801 core_message: added delete message caps
http://git.moodle.org/gw?p=moodle.git;a=commit;h=4582308508e1545cb297a41c9a6e5011b4cc5fb4
http://github.com/moodle/moodle/commit/4582308508e1545cb297a41c9a6e5011b4cc5fb4
+ 3.0 en [site:deleteanymessage,core_role]
+ 3.0 en [site:deleteownmessage,core_role]