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/sessions/overview/main.go

@@ -46,5 +46,5 @@ func main() {
 	app.Get("/login", login)
 	app.Get("/logout", logout)
 
-	app.Run(iris.Addr(":8080"))
+	app.Listen(":8080")
 }