Appends the [Forwarded](https://tools.ietf.org/html/rfc7239) header to the request.
Annotates HTTP method, uri, and status code, content-type, and content-length.
Coerces HTTP proxy requests to normal requests.
Appends the [Via] (https://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-14#section-9.9) header to the request and response.
Appends the [Via] (https://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-14#section-9.9) header to the request and response. After the header is appended, the message is upgraded to HTTP/1.1.
Appends the [Forwarded](https://tools.ietf.org/html/rfc7239) header to the request.
Possible future additions: * parse incoming X-Forwarded-* from legacy proxy services and convert to Forwarded