Update DisplayableDeck.java

Un commented the display Deck method and added string "UNO BACK"
Update Card.java

added the getCardImg method, this is for the discard instance in displayableDiscard to get the string name for the image in the pictures folder
Update DisplayableDiscardPile.java

added parameters to getImage
Merge pull request #3 from skwerlbergamot/master

various changes in calling an image of a card