fix golint issues in rest (#529)

rest/handler/gunziphandler.go

@@ -10,6 +10,7 @@ import (
 
 const gzipEncoding = "gzip"
 
+// GunzipHandler returns a middleware to gunzip http request body.
 func GunzipHandler(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if strings.Contains(r.Header.Get(httpx.ContentEncoding), gzipEncoding) {