Update iris code to the latest (v11)

Author: kataras

iris/server.go

@@ -1,12 +1,11 @@
 package main
 
-import ("github.com/kataras/iris")
+import "github.com/kataras/iris"
 
 func main() {
-	iris.Config.Charset = "UTF-8" // this is the default, you don't have to set it manually
-
-	iris.Get("/", func(ctx *iris.Context) {
-		ctx.Text(iris.StatusOK, "Hello World!")
+	app := iris.New()
+	app.Get("/", func(ctx iris.Context) {
+		ctx.WriteString("Hello World!")
 	})
-	iris.Listen(":8080")
+	app.Run(iris.Addr(":8080"))
 }