Split code in respective files.

Resource method name change.

Route list func

middleware/helmet_test.go

@@ -10,7 +10,7 @@ import (
 )
 
 func TestHelmet(t *testing.T) {
-	r := mux.NewRouter()
+	r := mux.New()
 	r.Use(Helmet(HelmetOption{}))
 	r.GET("/hello", func(writer http.ResponseWriter, request *http.Request) {
 		_, _ = writer.Write([]byte("hello there"))