examples: replace all app.Run(iris.Addr(...)) with app.Listen just for the shake of simplicity, both are doing the same exact thing as it's described on the http listening first example.

Former-commit-id: d20afb2e899aee658a8e0ed1693357798df93462

_examples/mvc/hello-world/main.go

@@ -50,7 +50,7 @@ func main() {
 	// http://localhost:8080/ping
 	// http://localhost:8080/hello
 	// http://localhost:8080/custom_path
-	app.Run(iris.Addr(":8080"))
+	app.Listen(":8080")
 }
 
 // ExampleController serves the "/", "/ping" and "/hello".