Git commits in Moodle 2.5.6 by Gilles-Philippe Leblanc

commit f29f455e8d3bf4a3a696892f22116a66426b2bbb
Author: Gilles-Philippe Leblanc <gilles-philippe.leblanc@umontreal.ca>
Date:   Fri, 14 Mar 2014 19:37:09 +0800
Tag:    v2.5.6

MDL-44585 grade_import: Restrict the accepted types in the gradebook import