add Authorization token to Dropzone.options.uploadForm only if it is present in the url

[p-andrey]

Hello.

Summary of the change:

This PR add Authorization header to Dropzone config just if they present in url.

My problem

When my site is blocked by authorization (special), I cannot upload files, because dropzone setting overrides the Authorization header.

Same PR

#660

Thanks for this nice package.

[streamtw]

Thanks @p-andrey !