check_dark_archive command and tests
Add sauce testing.
Fix test.
Merge pull request #607 from jcushman/dev-dark_archive

Just merging this straight in, since it doesn't affect the server code, just tooling.
Added error message if feedback form is submitted without email.
Fixes #608
Merge branch 'develop' of github.com:harvard-lil/perma into develop
Fix IE archive creation; improve Sauce tests.
Merge branch 'dev-sauce' of https://github.com/jcushman/perma into jcushman-dev-sauce
Merge branch 'jcushman-dev-sauce' into develop