3.20-test1

* "`DOCUMENT_ROOT` is symlink" bugfix
* Uniform is replaced with my alternative - transForm
(http://jquery.sunhater.com/transForm)
* Improved image viewer
* Improved drag & drop upload functionality. Progress bars in a dialog
box.
* Supports drag & drop images from external html page
* Language dropdown in settings toolbar
* No border-radius when scrollbar(s) exists into files and folders panes
* `_dropUploadMaxFilesize` option is added. (Drag & dropping bigger
files cause crash the web browser)
* `composer.json` file added
* Changelog file is now in Markdown format
* 4 new labels to translate