Use initializeNewLog rather than instantiate the UserLog
Summary:
Use initializeNewLog rather than instantiate the UserLog,
Closes T4912
Test Plan: Run install-certificate
Reviewers: #blessed_reviewers, btrahan
Reviewed By: #blessed_reviewers, btrahan
Subscribers: epriestley
Maniphest Tasks: T4912
Differential Revision: https://secure.phabricator.com/D8887