Minor bin/aphlict cleanup

Summary: Ref T10697. This just improves a couple of minor bin/aphlict things: make argument parsing more explicit/consistent, consolidate a little bit of duplicated code.

Test Plan: Ran all bin/aphlict commands.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10697

Differential Revision: https://secure.phabricator.com/D15698