anchor.diff:  ### Deck (DeckWithoutId)
   + id: `12345678-9012-3456-7890-123456789012` (string, required) - Deck UUID, 36 chars, 8-4-4-4-12 chars
   + creatorEmail: `test@mail.com` (string, required) - email of a user which created a deck
  ++ creationDate: `2016-05-03 01:25:44.629` (string, required) - date od Deck creation 'in YYYY-MM-DD hh:mm:ss.SSS' format
   
   ### FlashcardWithoutId (object)
   + question: `Sample question` (string, required) - question attribute for Flashcard
  
positive.code: 
  # Change log
  
  ## 28/04/2016 arka
   - fixed tips to current state
  ## 28/04/2016 toja
  
negative.code: + deckId: `291acb97-6f50-4522-8049-aee0b4e16b42` (string, required) - Deck UUID, 36 chars, 8-4-4-4-12 chars
  
  ### TipWithoutId (object)
  + essence: `Sample content` (string, required) - content of a Tip
  + difficult: `8` (number, required) - difficult level of a Tip, must be between 0 and 10
  
  ### Tip (TipWithoutId)
  + id: `12345678-9012-3456-7890-123456789012` (string, required) - tip UUID, 36 chars, 8-4-4-4-12 chars
  