[IOT-898] Propagate result of CA discovery/listen start call.

[IOT-898] Propagate result of CA discovery/listen start call.

Capture and return the result of CA discovery and listen start
function calls to allow for better differentiation of transport
adapter initialization and communication errors.

Change-Id: Ib5717600708e36792c020cb1c3b9f9caeaad9839
Signed-off-by: Ossama Othman <ossama.othman@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/4443
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jon A. Cruz <jonc@osg.samsung.com>