Consider making raw TLS over TCP based proxy


This is currently an HTTP-based proxy.  It could easily be made to forward raw bytestreams over TLS/TCP, but handling HTTP is needed in order to inject measurement data into the request or reponse headers.  If we made the header-injection optional we could make this protocol-agnostic.

@0x416e746f6e proposed that there are cases where this would be desirable. 