hubot ping script: Move help strings close to their rules; add more secrets.

Change-Id: I2b5fb5e4c2c45e9f5083f9f582e1bb5a9284707b
Port `codex` hubot script.

It would be nice to allow optional quotation marks to better distinguish
puzzle/answer/round/round group names.

Change-Id: Ibcd33175ef4225c8247e1936df9d1d1adddb08f6