Extracting Filename when Empty String fails

[adamup928]

When extracting the filename parameter for a multipart request, currently, if the filename is an empty string, Busboy does not emit a file event.

This is because when checking for a filename here:

else if (disp.params.filename)

that line will evaluate to false since ('' == true) evaluates to false.

I suggest changing that line to read:

else if (disp.params.filename !== undefined)

Hope this helps!