[IOT-825] Explicit discovery to get secure port during provisioning

[IOT-825] Explicit discovery to get secure port during provisioning

Issue : If provisiong candidate device doedn't have any secure resource,
        Provisioning Tool can't get secure port.
Solution : In order to get secure port, try explicit discovery
           with /oic/res?rt=oic.sec.doxm. instead of /oic/res
Related jira : https://jira.iotivity.org/browse/IOT-825

[Patch-2] : apply Sachin's comment

Change-Id: I6d6986f64af7ef24dd28ebada477613f30ee1e04
Signed-off-by: js126.lee <js126.lee@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/4131
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Sachin Agrawal <sachin.agrawal@intel.com>