Add failing EngineerStore unarchive test. We'll need to create a test engineer.archive file and copy it to the simulator or iPhones documents directory before this test will pass. So we can wait until after the code can create one, or we can build a utility app that includes EngineerStore and creates a few sample engineer objects and then archives them, and use that file. An alternative would be to create a temporary method in EngineerStore that creates a few sample engineers and adds them to the allEngineers array.