Gun with proxy
- Forked from https://github.com/ninenines/gun
- Reuse HTTP/1.1, HTTP/2 Websocket client
- Reuse proxy from hackney
- Add feature to determine traffic usage via callback function
- Refactor test for ExUnit
- Keep tracking upstream source code
- Remove unused things : event_handler, socks, raw, tls_proxy
- Support simpler proxy code from hackney