setting content-length to '0' is apparently required to support nginx as a back-end ( https://github.com/andreareginato/node-http-proxy/commit/642a838093286da3b3b84726e38dcf3f8748f7f0 )
Fix truncated chunked responses ( https://github.com/jpetazzo/node-http-proxy/commit/f035b2f0257384d9ea0629f1ed05bf7c13617373 )
do not mess with the handshake data when there is no need.