Author: Rajesh Taneja
MDL-40044 Roles: Added role_deleted event and replaced related add_to_log
http://git.moodle.org/gw?p=moodle.git;a=commit;h=a7524e354bc35418980596cda280bedc2ec6e697
http://github.com/moodle/moodle/commit/a7524e354bc35418980596cda280bedc2ec6e697
+ 2.6 en [eventroledeleted,core_role]