Incorporate code for managing Cleanup of Stale Channels

[hollomancer]

Another slack utilizes the following Python-based bot for cleaning up stale channels;
https://github.com/randsleadershipslack/destalinator

It has four components;

• Warner - The Warner notifies channels that have been inactive for a period of time.
• Archiver - The archiver archives channels that have been inactive for a period of time.
• Announcer - The Announcer will notify a channel of all new channels created within a period of time.
• Flagger - The Flagger uses a ruleset defined in a specific channel to perform actions such as notifying channels of messages that have received a certain number of reactions.

I'm wondering how much of this we can incorporate.