(Issue #3781) Ensure uploaded file(s) have actual content
(Issue #3781) More general approach
(Issue #3781) Add error message when no content identified
fix additional problems with dropzone-based uploads
(Issue #3781) modify error messages
(Issue #3781) handle dropped folders (and files) in Chrome
add more forgiving error handling
(Issue #3781) trigger event in all cases (so error message may be displayed)
(Issue #3781) check dropped files for validity and display error if appropriate
(Issue #3781) follow up from review
(Issue #3781) fix formatting from review
(Issue #3781) move duplicate l10n keys to common ui bundle
Merge branch 'master' of https://github.com/oaeproject/3akai-ux into issue3781
(Issue #3781) move duplicate l10n keys to shared/oae/bundles/ui
Merge pull request #3781 from sathomas/issue3781

Dragging a folder to Upload Files locks Firefox when upload is attempted.