Allow logged-out users to accept invites on nonpublic installs

Summary:
If your install isn't public, users can't see the Auth or People applications while logged out, so we can't load their invites.

Allow this query to go through no matter who the viewing user is.

Test Plan: Invite flow on admin.phacility.com now works better.

Reviewers: chad, btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D11765