Watch all repositories

[omerlh]

Hey!
I really liked this bot, but it will be even better if it could watch all repositories in the org instead of specifying which repos to watch.
Happy to contribute a PR.

[DentonGentry]

By all means, please send a PR. It would need to be an optional function or configuration option, as some deployments (including ours) do want just a subset of repositories to be watched.