Add a third, simple, example for folder structuring as requested at https://github.com/kataras/iris/issues/748

One change to code base but it will be described at the next version:

Error Handlers (`app.OnErrorCode/OnAnyErrorCode`)  respect the `app.UseGlobal`'s middlewares now (not the `app.Use` for reasons we can all understand, hopefully).


Former-commit-id: ec97bbb04548f9932cf4d7b950be513b70747bcb

_examples/structuring/handler-based/middleware/identity/identity.go

@@ -0,0 +1,33 @@
+package identity
+
+import (
+	"time"
+
+	"github.com/kataras/iris"
+
+	"github.com/kataras/iris/_examples/structuring/handler-based/bootstrap"
+)
+
+// New returns a new handler which adds some headers and view data
+// describing the application, i.e the owner, the startup time.
+func New(b *bootstrap.Bootstrapper) iris.Handler {
+	return func(ctx iris.Context) {
+		// response headers
+		ctx.Header("App-Name", b.AppName)
+		ctx.Header("App-Owner", b.AppOwner)
+		ctx.Header("App-Since", time.Since(b.AppSpawnDate).String())
+
+		ctx.Header("Server", "Iris: https://iris-go.com")
+
+		// view data if ctx.View or c.Tmpl = "$page.html" will be called next.
+		ctx.ViewData("AppName", b.AppName)
+		ctx.ViewData("AppOwner", b.AppOwner)
+		ctx.Next()
+	}
+}
+
+// Configure creates a new identity middleware and registers that to the app.
+func Configure(b *bootstrap.Bootstrapper) {
+	h := New(b)
+	b.UseGlobal(h)
+}