Added header bar and deck images.

Added a centered header bar for the game.
Added a deck image for each player.  Currently just a placeholder for later adding card images.
Added playNext button and placeholder text.

Added an input button that calls playRound with the two hands.
Fixed a bug that showed the incorrect cards for playCard().
Added placeholder text in the middle of the screen to show the user what cards were played.
Changed playCard to change the visible text.

Changed both playCard and playRound to change text lines in the document to show the user the
current state of the game.  These will be triggered when the playNext button is triggered.