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.
I moved it to the dspace.cfg file because of https://github.com/datadryad/dryad-repo/pull/664#issuecomment-52046615. Should I move it back?