Support --json output on all CLI commands for nicer command pipelining

[rvagg]

Enforce this across all commands, come up with a pattern to provide output that's either nice stdout or JSON, perhaps a very basic template processing system that takes the same input and spits out the appropriate output.

[SgtPooki]

This will make using the github action (#49) much easier.

[SgtPooki]

FYI: gh-action will not depend on using json, we have too much UI in the action, so we'll likely keep using JS, but will simplify the #60 changes with #80