Cards are not random

[andreldm]

The fix should be in file src/card/card-store.ts.
Instead of using two states (FREE, USED), a third one should be introduced: USING.
So the card lifecycle will be: FREE -> (getNewCard) USING -> (discard) USED
Once there is no free card, the getNewCard method should reset all USED to FREE and shuffle them.

[andreldm]

@geanpeixoto what do you think? The implementation is pretty straightforward, but I don't know how write a unit test for this.