Avoid to call uploadNext

Since all files will start to be uploaded at the time the files are added into the queue, we can remove the call to the uploadNext() method on the FileUploaded() event and simply check if all the files are being uploaded to trigger the UploadComplete() upload event .

This change also wins some performance since the uploadNext() event is making a loop for all the selected files to be upload.
Merge pull request #2 from Pablopolus/patch-2

Avoid to call uploadNext