Author: Hai Nguyen Van
MDL-87190 filepicker: clarify error when dragging a folder into picker
http://git.moodle.org/gw?p=moodle.git;a=commit;h=657ab1589757a069515dd2a169724b3a3b56da77
http://github.com/moodle/moodle/commit/657ab1589757a069515dd2a169724b3a3b56da77
+ 5.0 en [upload_error_folders_not_supported,repository_upload]
+ 5.0 en [upload_error_folders_not_supported_title,repository_upload]