Update unittest of notification-manager.

Update unittest of notification-manager.

Adding unittest for HostingObject Class,
and fixing release of smart pointer.

Change-Id: Ia27070b5908c5b42348a430dc602e136b70a9217
Signed-off-by: jyong2.kim <jyong2.kim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2911
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Hun-je Yeon <hunje.yeon@samsung.com>
Reviewed-by: Madan Lanka <lanka.madan@samsung.com>
(cherry picked from commit fb5bd9d3850692564af58daa92721c93720528e6)
Reviewed-on: https://gerrit.iotivity.org/gerrit/2919