Cleaned up intention in main.qml
Messing around with card selection
Inconsistent var naming scheme in the qml files will be
sorted out eventually
qml/main.qml:
* Replaced the text elements in the listview delegates with
Card properties
* Added properties selectedCardValue, selectedCardSuit, and
selectedCardStack for card selections.

qml/Card.qml:
* Added the properties bg, cardvalue, cardsuit, cardisfaceup
properties are tentatively named; don't know how to deal with var
name conflicts yet
* Added Text element which renders cardvalue, cardsuit, and
cardisfaceup
* Added some wip code for card selection handling:
    * Added MouseArea element. Changes table's selectedCardValue and
selectedCardSuit to the card's respective values when clicked
    * Added selected state which changes the card's color when selected