[About] Add controllers

Add initial implementations of controllers to support showing
the About dialog on logo click, WTD-667.

platform/commonUI/about/src/LogoController.js

@@ -0,0 +1,18 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        function LogoController(overlayService) {
+            return {
+                showAboutDialog: function () {
+                    overlayService.createOverlay("overlay-about");
+                }
+            };
+        }
+
+        return LogoController;
+    }
+);