POC: demo one device controlling another

[mitra42]

• [X] #54
• [X] Sensor_SHT85 measuring humidity and temp
• [X] Two devices - one with relay, other with sensor
• [ ] Build an adapter to demo the relay - box, Mains plug & socket, maybe 5V power supply, ESP8266 Relay
• [ ] control_xxx to watch humidity exceed certain level and send a message
  • [ ] #43
  • [ ] configuration of control to subscribe to humidity (from same device)
  • [ ] configuration of that control to send message to a certain other device B/relay
  • [ ] Advertisement that specifies a value wants to know a digital topic to connect to
  • [ ] Slider control for humidity level
  • [ ] Expand slider control to give hysteresis (fatter bar) - maybe cursor turns into vertical line
• [ ] HTML control to select a topic to configure from digital outputs
• [ ] Test that it all works together.