text: POST /upload HTTP/1.1
  Host: localhost:8080
  Content-Type: multipart/form-data; boundary=----TLV0SrKD4z1TRxRhAPUvZ
  Content-Length: 178
  
  ------TLV0SrKD4z1TRxRhAPUvZ
  Content-Disposition: form-data; name="upload"; filename="plain.txt"
  Content-Type: text/plain
  
  I am a plain text file
  
  ------TLV0SrKD4z1TRxRhAPUvZ
  