Secure some securable references (#12)
Secure some securable references (#12)

When I landed the previous commit,
2dbfb19f51812831d2c9c1cfdcb09a9fb7632515, I
inadvertently reverted its parent,
89bbdf51ea06b50227eae0d58d34e723e16f5977. This commit
re-applies that change.

kr/secureheader