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: I2815cc30c51ad538e2069a87b7f405e602c585c4
Signed-off-by: Hwankyu Jhun <h.jhun@samsung.com>