#399 - fix callback context
#399 - fix callback context

SimonWaldherr/uploader,SimonWaldherr/uploader,SimonWaldherr/uploader,SimonWaldherr/uploader,SimonWaldherr/uploader,SimonWaldherr/uploader,FineUploader/fine-uploader,FineUploader/fine-uploader,FineUploader/fine-uploader,SimonWaldherr/uploader