Middleware upgrade (#554)

* Adds root level middleware

* Added todo

* Better way for extensions to be added.

* Bad conflict merge?

images/hello/hello.go

@@ -11,7 +11,11 @@ type Person struct {
 }
 
 func main() {
-	p := &Person{Name: "World"}
+	n := os.Getenv("NAME") // can grab name from env or input
+	if n == "" {
+		n = "World"
+	}
+	p := &Person{Name: n}
 	json.NewDecoder(os.Stdin).Decode(p)
 	fmt.Printf("Hello %v!\n", p.Name)
 }