Card Categories are serialized as an Array

[BrennanAyers]

For the Frontend, to handle Single or Multiple categories, the Card attribute of category should be an Array of categorical (Action, Money, Victory) identifier strings.
We should store these in the DB as a String of comma separated values, which we then can serialize as an Array.

UPDATE

This has been set up correctly on the Player State endpoint, will need to be implemented on the Game State endpoint.

[DavisC0801]

Rolled into #34 and #49