Allow the Aphlict server to bind to localhost

Summary: If you are running the Aphlict server behind a reverse proxy (such as nginx) then there's no need to bind to 0.0.0.0. Add a --client-host flag to aphlict_server.js to allow binding to a different hostname. Also changed the other flags for consistency and clarity.

Test Plan: Started, stopped and debug the Aphlict server.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11288