Consider Slack integration for some administrative tasks

[mp911de]

We have a few administrative tasks, like signature creation or querying the signature status of a particular user that would be handy if they were performed via a slack bot. Slack gives an authenticated context (e.g. a slack channel) and provides logging functionality (who did what) for changes. We could use Slack + Pivotal CLA in within channels for state-altering operations (documentation + announcement) and enable additionally private messages to the slack bot for individual query operations (has a user signed the CLA/which one/…).