move example flash-messages to sessions example folder and change httptest example with basicauth

Former-commit-id: 3c5f6c97629a2a6ae44e62f2900edd32c0329b50

_examples/intermediate/sessions/flash-messages/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/context"
+	"github.com/kataras/iris/sessions"
+)
+
+func main() {
+	app := iris.New()
+	// output startup banner and error logs on os.Stdout
+
+	sess := sessions.New(sessions.Config{Cookie: "myappsessionid"})
+	app.AttachSessionManager(sess)
+
+	app.Get("/set", func(ctx context.Context) {
+		ctx.Session().SetFlash("name", "iris")
+		ctx.Writef("Message setted, is available for the next request")
+	})
+
+	app.Get("/get", func(ctx context.Context) {
+		name := ctx.Session().GetFlashString("name")
+		if name == "" {
+			ctx.Writef("Empty name!!")
+			return
+		}
+		ctx.Writef("Hello %s", name)
+	})
+
+	app.Get("/test", func(ctx context.Context) {
+		name := ctx.Session().GetFlashString("name")
+		if name == "" {
+			ctx.Writef("Empty name!!")
+			return
+		}
+
+		ctx.Writef("Ok you are comming from /set ,the value of the name is %s", name)
+		ctx.Writef(", and again from the same context: %s", name)
+
+	})
+
+	app.Run(iris.Addr(":8080"))
+}