[IOT-1652] Modify confirmed certificate OTM to use vendor namespace

[IOT-1652] Modify confirmed certificate OTM to use vendor namespace

Confirmed Certificate OTM is vendor-specific OTM
and hence oic.sec.namespace is replaced by x.org.iotivity.
https://jira.iotivity.org/browse/IOT-1652

Patch #1: Initial upload

Change-Id: Ifa3c4f9119307064e27c90f2581cdb6d4765be13
Signed-off-by: Jongmin Choi <jminl.choi@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/15461
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jongsung Lee <js126.lee@samsung.com>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>
(cherry picked from commit 7d1493d3288a5b121c70b429d26218ec91ff664c)
Reviewed-on: https://gerrit.iotivity.org/gerrit/15537