Transition to SPAN published MQTT/REST api

[cayossarian]

Migrate to documented MQTT/REST api starting with firmware

See also:

• SPAN API beta officially released. span#173
• Migration to official SPAN API span#174

https://github.com/spanio/SPAN-API-Client-Docs

[dcj]

SpanPanel/span#173 (comment)

And specifically: https://github.com/electrification-bus/python-sdk

Note the OpenAPI spec endpoint in the REST API:

And the Homie schema endpoint