Author: Simey Lameze
MDL-66034 core_role: implement capability unassigned event
http://git.moodle.org/gw?p=moodle.git;a=commit;h=a98bafa163378a42607c85752930e3a5cd3f0385
http://github.com/moodle/moodle/commit/a98bafa163378a42607c85752930e3a5cd3f0385
+ 3.8 en [eventcapabilityunassigned,core_role]