Added Deck protection from null
Decks can now no longer be created with a null value for the name.  The card list will also remain null until cards are added.

The serializer now only adds a card field if the cards field is not null, and the deserializer sets cards to null if there is no card field.

Committed by: Alec Thompson - ajthompson
Merge branch 'sbl-dev' into exp-deck
Merge pull request #225 from ajthompson/exp-deck

Added null value protections in Deck and it's serializers