R1:d4b78af10271

Allow `DivinerPublisher` to be specified as a flag

Summary: Allow the `DivinerPublisher` subclass to be specified via `./bin/divner generate --publisher ...`. In particular, this allows use of the (mostly broken) `DivinerStaticPublisher`.

Test Plan: Ran `./bin/diviner generate --publisher DivinerStaticPublisher`

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11588