Author: John Okely
MDL-56646 assign: Add ability to fix errant grades
http://git.moodle.org/gw?p=moodle.git;a=commit;h=167507dcf853206bbfe904ffdef049f96b3c9ec9
http://github.com/moodle/moodle/commit/167507dcf853206bbfe904ffdef049f96b3c9ec9
+ 3.2 en [fixrescalednullgrades,mod_assign]
+ 3.2 en [fixrescalednullgradesconfirm,mod_assign]
+ 3.2 en [fixrescalednullgradesdone,mod_assign]