Add a "verbose" mode to daemons for activity logging

Summary: See discussion in T1389. Some daemon issues are pretty painful to troubleshoot over IRC, add a log() method activated by a --verbose flag to allow conditional activity logging at a more useful level than "errors only" (which isn't verbose enough) or "--trace" (which is far too verbose).

Test Plan: Ran "nice" daemon in verbose and non-verbose modes.

Reviewers: vrana, jungejason, edward, aurelijus

Reviewed By: vrana

CC: aran

Maniphest Tasks: T1389

Differential Revision: https://secure.phabricator.com/D2795