Author: Huong Nguyen
MDL-80850 Javascript: Add new core/dropzone module
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b0220f27cb33965dda5ad3894ca79b07f46eb976
http://github.com/moodle/moodle/commit/b0220f27cb33965dda5ad3894ca79b07f46eb976
+ 4.4 en [addfilesdrop,core]