Ensure that every prompt is based on a flag or argument

[blacksails]

In order to enable all commands to be scripted or run in CI, we need to support that they are run in a non-interactive manner.

Most importantly:

• rig config it should be easy to manipulate the configuration.
• rig capsule deploy it should be easy to deploy images.
• rig capsule image create it should be easy to add images to capsules.