Fix only a single card being able to be played

`Array.splice` always returns an array, so we need to get the actual
element from that array, instead of unshifting the array onto the layed
off card stack.
Send a user his new set of cards after a turn

Instead of sending them to the next user, which should be send an update
of his own cards as well just to make sure he has an up-to-date set.