add h2 header manually for pre-go 1.9 users when manually key files are being used

Former-commit-id: edf521fc02de87b53cd3bdf0b8e77610dd535862

_examples/routing/writing-a-middleware/per-route/main.go

@@ -0,0 +1,36 @@
+package main
+
+import "github.com/kataras/iris"
+
+func main() {
+	app := iris.New()
+	app.Get("/", before, mainHandler, after)
+	app.Run(iris.Addr(":8080"))
+}
+
+func before(ctx iris.Context) {
+	shareInformation := "this is a sharable information between handlers"
+
+	requestPath := ctx.Path()
+	println("Before the mainHandler: " + requestPath)
+
+	ctx.Values().Set("info", shareInformation)
+	ctx.Next() // execute the next handler, in this case the main one.
+}
+
+func after(ctx iris.Context) {
+	println("After the mainHandler")
+}
+
+func mainHandler(ctx iris.Context) {
+	println("Inside mainHandler")
+
+	// take the info from the "before" handler.
+	info := ctx.Values().GetString("info")
+
+	// write something to the client as a response.
+	ctx.HTML("<h1>Response</h1>")
+	ctx.HTML("<br/> Info: " + info)
+
+	ctx.Next() // execute the "after".
+}