The proxy will now try to detect what protocol new connections are
using, and route them accordingly. Specifically:
- HTTP/2 stays the same.
- HTTP/1 is now accepted, and will try to send an HTTP/1 request
to the target.
- If neither HTTP/1 nor 2, assume a TCP stream and simply forward
between the source and destination.
* tower-h2: fix Server Clone bounds
* proxy: implement Async{Read,Write} extra methods for Connection
Closes#130Closes#131
Sean McArthur