Git commits in Moodle 2.4.7 by Jody Steele

commit a10d621fc50e5fdceb5dec4df8dd04ba10387a55
Author: Jody Steele <steelej@queensu.ca>
Date:   Wed, 16 Oct 2013 23:19:34 +0800
Tag:    v2.4.7

MDL-38628 mod_assign: Allow a user to specify "No Grade" when grading an assignment submission