Add --status option to return single value

[martin-g-it]

Added the option --status to return single status value.

Useful to retrieve single values to update ie. Domoticz custom sensors.
Option should work for plain_coap and coap; not included for plain http (class HTTPAirCli)
Tested and working for CoAPCli class; the PlainCoAPAirCli class / protocol I cannot test.

[martin-g-it]

Example output (coap protocol)

[rgerganov]

Not sure about this. Why not simply grep the key you are looking for?

[martin-g-it]

Agree, in fact it would be even better if the -d (debug) would only spit out a true JSON (with " quotes instead of ')
Or have this status printed upon a arg like -json

[martin-g-it]

also the cl (Child Lock) value should then be within quotes instead of plain True/False

[Cyber1000]

@martin-g-it
I did a bigger refactoring in #81 (formatting is done in a single base class, so only one entry point in the future).
Beside the uppercase "False" this is valid json, but I've looked into this and will make a new PR after my PR is merged.

Just to mention this:

• false/true without quotes is a boolean in json and is correct -> see boolean-datatype in https://www.w3schools.com/js/js_json_datatypes.asp
• actually it should be lowercase: true/false instead of True/False
• instead of pprint we should use something like print(json.dumps(status, indent=4))
  • this doesn't change/uppercase the values, so false will stay false (instead of False, which is caused by pprint)