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

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/bootstrap/routes/index.go

@@ -0,0 +1,11 @@
+package routes
+
+import (
+	"github.com/kataras/iris/v12"
+)
+
+// GetIndexHandler handles the GET: /
+func GetIndexHandler(ctx iris.Context) {
+	ctx.ViewData("Title", "Index Page")
+	ctx.View("index.html")
+}