Add JSON Output to CLI via Flag

[js-truework]

I'd love to be able to show the output from the API via a flag, e.g. --output=json or --json, when calling from the CLI. This can be helpful in showing what the API results will look like and designing integrations.

Happy to write this feature myself if this project is still maintained, since I suspect it would be useful for others, and don't think it would be very difficult to add.