Fix issue where accessing HTTP domain would override HTTPS cookie

Summary: This fixes an issue where visiting http://code.redpointsoftware.com.au/ would log you out of https://code.redpointsoftware.com.au/

Test Plan: Applied this patch to a live server and saw the issue go away.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8244