Handle abnormal exit

Handle abnormal exit

Whlie calling widget_app_exit(), the widget app sends the normal
termination signal to the amd. If the amd doesn't get the signal when
the widget app is dead, the amd will send the widget fault signal to
the widget viewer.

Requires:
 - https://review.tizen.org/gerrit/#/c/131674/ [aul-1]
 - https://review.tizen.org/gerrit/#/c/131685/ [amd]
 - https://review.tizen.org/gerrit/#/c/131692/ [widget-service]
 - https://review.tizen.org/gerrit/#/c/131695/ [widget-viewer]

Change-Id: I60076b893ef36c8a43e43669746393b7b98b877f
Signed-off-by: Hwankyu Jhun <h.jhun@samsung.com>