Support protocol specific topic (`/ul/<apiKey>/<deviceId>`)

[mapedraza]

IoT agents are going to drop the support for the legacy MQTT Topic format (/<apiKey>/<deviceId>) soon. The only supported format will be the one that includes the protocol in advance (i.e. /ul/<apiKey>/<deviceId>) as described in the documentation

This is the PR
telefonicaid/iotagent-json#633

[jason-fox]

This tutorial will need to be updated after the next release of the Ultralight agent to:

• Update the README and alter any direct MQTT commands of the form /<apiKey>/<deviceId> to /ul/<apiKey>/<deviceId>.
• Use the updated version of the test harness and add MQTT_TOPIC_PROTOCOL=ul to the docker-compose.yml

[jason-fox]

closed by 6d8eb1f