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/middleware/main.go

@@ -20,7 +20,7 @@ func main() {
 	// http://localhost:8080/other
 	//
 	// refresh every 10 seconds and you'll see different time output.
-	app.Run(iris.Addr(":8080"))
+	app.Listen(":8080")
 }
 
 func configure(m *mvc.Application) {

_examples/mvc/middleware/per-method/main.go

@@ -84,7 +84,7 @@ func main() {
 	m := mvc.New(app)
 	m.Handle(&exampleController{})
 
-	app.Run(iris.Addr(":8080"))
+	app.Listen(":8080")
 }
 
 type exampleController struct{}

_examples/mvc/middleware/without-ctx-next/main.go

@@ -51,7 +51,7 @@ func main() {
 
 	m.Handle(&exampleController{})
 
-	app.Run(iris.Addr(":8080"))
+	app.Listen(":8080")
 }
 
 func doneHandler(ctx iris.Context) {