Git commits in Moodle 2.8.9 by Lars Anderson

commit e4d7edbf4f564a1cebf4fe1ce92cb04f19a4088a
Author: Lars Anderson <lsa@its.aau.dk>
Date:   Wed, 25 Mar 2015 22:29:44 +0800
Tag:    v2.8.9

MDL-49561 core_calendar: Fix ical export for events with no duration