R1:0fc2464e0373

Minor tidying of `DivinerPublisher` classes

Summary: Self-explanatory. Also made a few methods `final`.

Test Plan: Eyeball it.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11598