document the state of each relevant repository

[cknoll]

it would be nice if a call to deploy.py would produce a txt file like:

• <repo1> at <branch1> (commit-date1, hash1) (remote: 3↑, 1↓)
• <repo2> at <branch2> (commit-date2, hash2) (remote: ✓)
• ...
  probably it needs a separate tool for this.