Include custom header PHID in header logo cache key
Summary: Ref T4214. Reduce the need for installs to purge caches.
Test Plan:
{F329350}
- Changed header twice.
- New one showed up without dirtying cache.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T4214
Differential Revision: https://secure.phabricator.com/D11965