Differentiate mqtt topic from maestro to sensors

[bleucitron]

The only topics sent to sensors are 'theSensorOwnId' and 'all'.
This is because the only info sent to sensors are commands. We should be able to send also data (like an array of bins).

Maybe add '/data' or '/cmd' to the topics.

[bleucitron]

This has been partially solved by cfb74ea.

Maybe we should add a .../cmd topic for commands.