CoAP over TCP transmission over BT

CoAP over TCP transmission over BT

currently, CoAP/UDP message format is used over BT-RFCOMM.
but BT-RFCOMM data transmission requires dedicated session
between devices and guarantees reliable data transmission
by its MAC & PHY layer. So, CoAP/TCP message format might
be more efficient for Bluetooth

Change-Id: I0b7752a1146efd1abbe74eb613c72346b99039e9
Signed-off-by: hyuna0213.jo <hyuna0213.jo@samsung.com>
Signed-off-by: jihwan.seo <jihwan.seo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/4447
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jon A. Cruz <jonc@osg.samsung.com>