Found bug in code about file-uploader

[KoulSlou]

@lamao Hi, I faced with the same problem. When I set encoding field to "multipart" uploader is not working and I receive message:

"Could not save uploaded file.The upload was cancelled, or server error encountered"

After some investigation, I understood that the problem is in index of $_FILES array. In constructor when script decide which type of uploader should be initialized (qqUploadedFileForm or qqUploadedFileXhr) index "qqfile" is checked in $_FILES. But there is no element with such index. And the problem in file upload.js in this code

if (this._options.encoding == 'multipart') {
        var formData = new FormData();
        formData.append(name, file);
        file = formData;
}

I just change formData.append(name, file); to formData.append("qqfile", file).

I'm not very confident in js and I appreciate any comments on this issue from plugin developers.