Check socket status

Check socket status

When handling the request that is app registration, AMD checks whether
the socket is listening or not. If the socket is listening, AMD will set
the 'true' to the socket_exists flag of the app status handle.

Requires:
 - https://review.tizen.org/gerrit/#/c/platform/core/appfw/launchpad/+/266359/
 - https://review.tizen.org/gerrit/#/c/platform/core/appfw/aul-1/+/266360/
 - https://review.tizen.org/gerrit/#/c/platform/core/appfw/amd/+/266361/

Change-Id: I5bbc23aad20ee987c7d637e287810c40a2d3ae71
Signed-off-by: Hwankyu Jhun <h.jhun@samsung.com>