Author: John Okely
MDL-39913 assignsubmission_file: Add validation
http://git.moodle.org/gw?p=moodle.git;a=commit;h=ea3f8fa0cbe5b077d74dcc741735ee9d4d93062f
http://github.com/moodle/moodle/commit/ea3f8fa0cbe5b077d74dcc741735ee9d4d93062f
+ 3.2 en [nonexistentfiletypes,assignsubmission_file]