Add a MQTT Section

[DevTown]

For the reason that there are some open MQTT-Servers of Hackerspaces out there, where the spaces publish some informations like door status, temps or sun collection , this section might be useful for div spaces.

[dbrgn]

Is this something that many spaces offer? If yes, which ones, and what data do they publish?

[DevTown]

The Chaostreff Recklinghausen has one and here will be published additional Infos like Doorstatus and div Temp and Voltages of the space.

[renzenicolai]

This issue about using MQTT as an additional (push instead of polling) source for the space state might be of interest: #93

Using MQTT in a more general sense is awesome, but I would like it if the change proposed here could be extended to contain a field that contains the name of the topic on which the space state is published, together with fields which give the value published when the space is open and closed (see the example given in my ticket).

[gidsi]

Hey,
we dicussed this PR in todays meeting and we don't see the additional value for all spaces without a standardized MQTT schema.
Can you share your use-case with us? Especially since all your examples are already provided by spaceAPI.

[rnestler]

I'd also love to see it as an ext_mqtt first in an endpoint with an example on how it is used.