Fix permissions on Aphlict log

Summary: Currently, the Aphlict server created the log file (if it doesn't exist) but then immediately fails with "Unable to open logfile". It seems that we don't set the permissions correctly.

Test Plan: Deleted log file and was able to start the Aphlict server.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11351