Jimmy Pocock - Puppy breeder 2

Updated Puppy Breeder with the Singleton instance. Created tests to make sure the hold requests work. All tests (new and previous) are passing. I will be updating this because I need to get the Sinatra files working properly with working with the Singleton instance, haven't tested that yet. I want to merge this with the puppy-breeder, but I'll wait and work on this branch until you tell me I can.