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/main_test.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/kataras/iris/httptest"
+)
+
+// TestApp runs by `$ go test -v`.
+func TestApp(t *testing.T) {
+	e := httptest.New(t, app.Application)
+
+	// test our routes
+	e.GET("/").Expect().Status(httptest.StatusOK)
+	e.GET("/follower/42").Expect().Status(httptest.StatusOK).
+		Body().Equal("from /follower/{id:long} with ID: 42")
+	e.GET("/following/52").Expect().Status(httptest.StatusOK).
+		Body().Equal("from /following/{id:long} with ID: 52")
+	e.GET("/like/64").Expect().Status(httptest.StatusOK).
+		Body().Equal("from /like/{id:long} with ID: 64")
+
+	// test not found
+	e.GET("/notfound").Expect().Status(httptest.StatusNotFound)
+	expectedErr := map[string]interface{}{
+		"app":     app.AppName,
+		"status":  httptest.StatusNotFound,
+		"message": "",
+	}
+	e.GET("/anotfoundwithjson").WithQuery("json", nil).
+		Expect().Status(httptest.StatusNotFound).JSON().Equal(expectedErr)
+}