Author: Luca Bösch
MDL-71352 gradereport_grader: Add icons for pass/fail.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e3958e5a8cb75ad2f0920a18d56c92efa414c19c
http://github.com/moodle/moodle/commit/e3958e5a8cb75ad2f0920a18d56c92efa414c19c
+ 3.10 en [fail,core_grades]
+ 3.10 en [pass,core_grades]