Testmode bug fix

Fixes https://trello.com/c/EgW3usAa/191-bug-testmode-doi-generation

Testmode DOIs don't need to be that complicated: according to http://ezid.cdlib.org/demo/simple, 10.5072/FK2. will suffice for making a demo DOI.
Actually the 10.5061 might be EZID and not Dryad. But we still always register "real" DOIs with dryad.