Automatically check for update

[mschwartz]

Description

modus-cli should periodically check for updates (to see if a newer version exists)

[mschwartz]

The package.json file can be downloaded and version checked against the existing one.

[mschwartz]

Related issue is that if modus-cli is used to download/merge guidelines, we can check the guidelines repo periodically to see if IT changed, too.

[grgur]

This would be nice. How would we track changes, tho? E.g.

1. Repo XYZ clones samples from Guidelines
2. Repo XYZ changes LICENSE
3. LICENSE is updated in Guidelines
4. Now what? How does modus-cli know that LICENSE is changed but e.g. ISSUE_TEMPLATE isn't?

[mschwartz]

We keep a version number in modus-cli-config.js and compare with version number in the guidelines repo.

If LICENSE exists, cli won't overwrite it unless you add the -o switch.

[grgur]

That would be nice. We need to prioritize all feature requests first