support permessage-deflate compression extension

Expected Behavior

"Per-message compression" has been adopted in many places, like Tomcat websocket. In order to leverage this, I hope websocket in actix-http and awc can support this extension by default. Due to current actix-http architecture, it's too hard to implement this in my code.

Current Behavior

Possible Solution

https://github.com/housleyjk/ws-rs/blob/master/src/deflate/extension.rs From above link, you can find a reference implementation for Rust.

RFC reference: https://tools.ietf.org/html/rfc7692