Bugfix while using multiple handlers (#415)

should pass updated req for remaining handlers

proxy.go

@@ -61,7 +61,7 @@ func isEof(r *bufio.Reader) bool {
 func (proxy *ProxyHttpServer) filterRequest(r *http.Request, ctx *ProxyCtx) (req *http.Request, resp *http.Response) {
 	req = r
 	for _, h := range proxy.reqHandlers {
-		req, resp = h.Handle(r, ctx)
+		req, resp = h.Handle(req, ctx)
 		// non-nil resp means the handler decided to skip sending the request
 		// and return canned response instead.
 		if resp != nil {