reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/auth/recaptcha/custom_form/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/kataras/iris/v12"
+
+	"github.com/kataras/iris/v12/middleware/recaptcha"
+)
+
+// keys should be obtained by https://www.google.com/recaptcha
+const (
+	recaptchaPublic = "6Lf3WywUAAAAAKNfAm5DP2J5ahqedtZdHTYaKkJ6"
+	recaptchaSecret = "6Lf3WywUAAAAAJpArb8nW_LCL_PuPuokmEABFfgw"
+)
+
+func main() {
+	app := iris.New()
+
+	r := recaptcha.New(recaptchaSecret)
+
+	app.Get("/comment", showRecaptchaForm)
+
+	// pass the middleware before the main handler or use the `recaptcha.SiteVerify`.
+	app.Post("/comment", r, postComment)
+
+	app.Listen(":8080")
+}
+
+var htmlForm = `<form action="/comment" method="POST">
+	    <script src="https://www.google.com/recaptcha/api.js"></script>
+		<div class="g-recaptcha" data-sitekey="%s"></div>
+    	<input type="submit" name="button" value="Verify">
+</form>`
+
+func showRecaptchaForm(ctx iris.Context) {
+	contents := fmt.Sprintf(htmlForm, recaptchaPublic)
+	ctx.HTML(contents)
+}
+
+func postComment(ctx iris.Context) {
+	// [...]
+	ctx.JSON(iris.Map{"success": true})
+}