Git commits in Moodle 2.5.x by Jonathan Champ

commit 37701d203833cb638c9a9ee50f72dca250f49534
Author: Jonathan Champ <jonathan_champ@ncsu.edu>
Date:   Thu, 20 Mar 2014 23:04:41 +0800
Tag:    v2.5.6

MDL-29572 Grade Import: Avoid creating invalid temporary rows; Provide feedback on error