Author: Ilya Tregubov
MDL-50650 core_grades: Validate minimum grade when importing grades
Also add behat test for max and min grade validation.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=ad3e6363f1f6e52e7f2832c7db21ed0287a50840
http://github.com/moodle/moodle/commit/ad3e6363f1f6e52e7f2832c7db21ed0287a50840
+ 4.1 en [gradevaluetoosmall,core_grades]