[4.0] Create Widget Application

[4.0] Create Widget Application

Create Widget Application using appcore-widget-base.

WidgetApplication - Application class to support Widget app

Widget            - Manage widget instance lifecycle.
                    It defines how widget works according to lifecycle

WigetApplication can have many types of Widget. And one Widget can have
instance more than one.

But now, User should define just one widget for widget application because
Dali can support only one window per application.

Change-Id: Idee6eb095352d103cfc942a4eb0a9502bf09bc4b