MQTT: Use / instead of . as topic separator

[bergie]

Currently MsgFlo always creates default queue names like role.PORT. However, with MQTT it would be good to use / as the separator, as then wildcards work correctly.

http://www.hivemq.com/blog/mqtt-essentials-part-5-mqtt-topics-best-practices

• msgflo-arduino
• msgflo-nodejs
• msgflo-python
• msgflo-rust

[jonnor]

Should fix all the libraries in one go

[jonnor]

Must ensure that we don't have code relying on the naming convention in Msgflo. Like setup without - -discover

[jonnor]

Since other systems may communicate using the topic name directly, this is a breaking change and must bump minor