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/routes/routes.go

@@ -0,0 +1,14 @@
+package routes
+
+import (
+	"github.com/kataras/iris/_examples/structuring/handler-based/bootstrap"
+)
+
+// Configure registers the nessecary routes to the app.
+func Configure(b *bootstrap.Bootstrapper) {
+	// routes
+	b.Get("/", GetIndexHandler)
+	b.Get("/follower/{id:long}", GetFollowerHandler)
+	b.Get("/following/{id:long}", GetFollowingHandler)
+	b.Get("/like/{id:long}", GetLikeHandler)
+}