NavigationView.qml : Added initialView property
Added OverlayView.qml
NavigationView.qml: Check the type of initialView before push to stack .
quickiosunittests : Supported to scan the QML files within example program to perform load test
Refactor NavigationView - NavigationBar becomes part of the NavigationView

 * The original NavigationView component that provides a stacked view has been moved to priv/NavigationStack
 * A new NavigationView component contains NavigationBar and NavigationStack and setup the binding automatically.
NavigationView.qml : Setup the tintColor of NavigationBar
NavigationView.qml : Attach the "navigationView" property to newly created view.
NavigationView.qml : The push() function may accept to take a parameter "options" , that will be passed to the createObject()
NavigationStack.qml : The push() - Report error when loading failed.
NavgiationStack.qml : Extra condition checking on push()
NavigationStack.qml : Fixed the problem that pushed() signal is not emitted for push()
Fix the broken test case
Merge pull request #5 from benlau/refactor-navigation-view

Refactor NavigationView and added new component