Update upload.js
Update upload.js

- Added support for "infoText" option. Now header, description and infoText works in same way as in other editors.
- Changed "alt_drop_zone_id" option to "alt_drop_zone". Now it can be any valid CSS selector.
- Moved preview out of description and into element content.
- Added dounleclick event to dropzone and fileDisplay to trigger the upload requester.

cunneen/json-editor,cunneen/json-editor