Basic slack check in / check out robot

To run, do npm install CHICO_TOKEN='{your slack bot token}' node ./chico.js

Invite chico to a channel. He'll look for "check in" and "check out" messages and remember who's checked in. (He'll understand any shortening too, like "chckin" or even "ci")

You can say "who's in?" to chico and he'll tell you who's checked into the current channel.

You can also say "john in?" (or any other name) to chico, and he'll tell you if someone with that nick is checked in, or the last time they were seen if they're checked out.