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.
That may work. Try it and see, and please document (in the cfg file) what the requirements are. I should have done this better myself.

Also, I placed the doi.localpart.testsuffix in the settings.xml file so that each dev server could vary it, and avoid collisions.