Author: Rossiani Wijaya
MDL-27161: fixed optional setting for 'require grading' to prevent page lock out
http://git.moodle.org/gw?p=moodle.git;a=commit;h=6ef4ef1ee554e4281cc3f1bf193cd38b9850f728
http://github.com/moodle/moodle/commit/6ef4ef1ee554e4281cc3f1bf193cd38b9850f728
+ 2.0 en [norequiregrading,mod_assignment]
+ 2.0 en [nosubmisson,mod_assignment]