Author: Davo Smith
MDL-60427 dndupload: detect attempts to upload folders
http://git.moodle.org/gw?p=moodle.git;a=commit;h=4e737cf37f2ac658732ed6db15bbb844e2da2bed
http://github.com/moodle/moodle/commit/4e737cf37f2ac658732ed6db15bbb844e2da2bed
+ 3.5 en [filereaderror,core]