Author: Stephen Bourget
MDL-44369 Calendar: add events for subscriptions
http://git.moodle.org/gw?p=moodle.git;a=commit;h=756e3c55c0c92c761ca3db2bcc9e7829c88c64f5
http://github.com/moodle/moodle/commit/756e3c55c0c92c761ca3db2bcc9e7829c88c64f5
+ 3.2 en [eventsubscriptioncreated,core_calendar]
+ 3.2 en [eventsubscriptionupdated,core_calendar]
+ 3.2 en [eventsubscriptiondeleted,core_calendar]