def upload_part(bucket, key, upload_id, part_number, data)
      response = @con.upload_part(bucket, key, upload_id, part_number, data)

      return response.headers['ETag']
    end
def upload_part(bucket, key, upload_id, part_number, data)
      response = @con.upload_part(bucket, key, upload_id, part_number, data)

      return response.headers['ETag']
    end
Upload a part for a multipart upload

 @param [String] bucket Name of bucket to add part to
 @param [String] key Name of object to add part to
 @param [String] upload_id Id of upload to add part to
 @param [String] part_number Index of part in upload
 @param [String] data Contect of part

 @return [String] ETag etag of new object. Will be needed to complete upload