Modify directory location and code refactoring "RCSDiscoveryManager"

Modify directory location and code refactoring "RCSDiscoveryManager"

- change directory location for "RCSDiscoveryManager.h" into resource-encapsulation/src/resourceClient
- code refactoring about RCSDiscoveryManager and RCSDiscoveryManagerImpl

Change-Id: I6790e5aec8cb80a1b62c8767e71256fb582c58bf
Signed-off-by: ChaJiwon <jw_wonny.cha@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/3113
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Madan Lanka <lanka.madan@samsung.com>
(cherry picked from commit db190254d8421cdbcea1c5c9292bb07d7fe29800)
Reviewed-on: https://gerrit.iotivity.org/gerrit/3199