Generic sensor processing code

[Colin]

@bkenobi

I still don't see how to accomplish this with the standard Influxdb inject node.

To quote from the help text for the node:
If msg.payload is an array containing two objects, the first object will be written as the set of named fields, the second is the set of named tags.

So msg.payload needs to be something like

[
  {temp: 75, humidity: 80, ...},
  {sensor: "some sensor", location: "some location"}
]

What is the sensor tag for?