Store principal profile pictures in new directory
Add ability to get permanent signed download url
(Issue 878) Fix intermittent test failure when creating a tenant
(Issue 878) Remove @api private from public method
(Issue 879) Fix intermittent test failure in revision filter test
Touched up some comments
Merge pull request #879 from mrvisser/issue-879

Intermittent Test Failure: verify reprocessing previews with a revision filter
Merge pull request #870 from mrvisser/new-profile-picture-uris

Signing improvements
Merge branch 'issue-878' of https://github.com/mrvisser/Hilary into issue-878
Small documentation improvement
Implement "Become User" functionality
Change oae-rest branch to become-user
Add indication in log when a user is impostered
(BecomeUser) Review followup
(BecomeUser) Filter HTTP headers when logging
(TravisCI) Print log errors on failure