[Escher] Responder can get a pointer to the parent App

We assume the root parent is the App. This works well because each view
controller is a Responder.

Change-Id: I5d90053949a4ffbdb78746cc85430a15138e48e7

apps/graph/graph/graph_controller.cpp

@@ -1,7 +1,7 @@
 #include "graph_controller.h"
 
-GraphController::GraphController() :
-  ViewController(),
+GraphController::GraphController(Responder * parentResponder) :
+  ViewController(parentResponder),
   m_view(GraphView())
 {
 }