Git commits in Moodle 2.9.3 by Lars Anderson

commit b7dffc34f5251886fd208348b43c805d501244eb
Author: Lars Anderson <lsa@its.aau.dk>
Date:   Wed, 25 Mar 2015 22:29:44 +0800
Tag:    v2.9.3

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