Cloud Interface Feature base on CoAP over TCP in CA Layer

Cloud Interface Feature base on CoAP over TCP in CA Layer

- modified libcoap library to support coap over tcp
- added new transport adapter and flag in CA
- linux platform can be supported
- TLS, IPv6, Keep alive and so on will be support 2nd phase
- https://wiki.iotivity.org/proposal_for_cloud_interface_in_iotivity

Change-Id: Ifcc0f78c1a5ca9d11e41498f712c0039213bd3d0
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/2298
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Patrick Lankswert <patrick.lankswert@intel.com>