Add --verbose support to phd

Summary:
Support the --verbose flag added in D2795 in phd. See T1389.

Also simplify argument generation a little bit.

Test Plan: Ran "nice" daemon with debug, daemon + verbose, daemon + no verbose.

Reviewers: vrana, jungejason, edward, aurelijus

Reviewed By: aurelijus

CC: aran

Maniphest Tasks: T1389

Differential Revision: https://secure.phabricator.com/D2797