text: Title: permessage-deflate compression support
  Body: Official Socket.IO [since 1.4.0](https://socket.io/blog/socket-io-1-4-0/) supports compression via [permessage-deflate (rfc7692)](https://tools.ietf.org/html/rfc7692).
  
  What would be needed to support that here? Or is it better to support that perhaps with a middleware or something?