fix for no content-length in header for download
fix for no content-length in header for download

When using a 3rd party S3 storage service (not AWS), there are
instances when the server returns a header without ‘content-length’
specified and instead uses  'transfer-encoding': 'chunked’. This
workout around will  create a writeable stream to save a file and still
emit progress total, but at 99%. When the transfer ends, the progress
will add 1 to be complete at 100%

andrewrk/node-s3-client,welll/node-s3-client