Add images for cards
Changes for browser compatibility
Merge branch 'css-shapes'
Combine separate card parameter vars into one.

* No need for cardValues because data is in cardValuesDic.
* No need to assign numbers and multiples. Sums are not going to be used to find sets.
Redefine isSet to work by comparing individual properties.

* No longer uses sums.
* Moved into the cards.js file and hung off the Card constructor.
Update isSet calls to call version hung off Card constructor.
Use cardParameters ids (property names) to iterate.
Remove sum.
Return single property value by looking it up on the card.
Make getSet a method on a table object.
Update calls to getSet to call as method on a table.
Remove gameplay.js import from index.html
Just get shape property value straight off card.
Remove part of card.getValues() that returns a single property value.
Move Table setup code into constructor.
Move deck setUp code into constructor.
Remove call to table.setUp().
Lowercase this.Deck: it's an attribute, not a constructor.
Make test of card existence more idiomatic.

* Best to explicitly check is not undefined.
* if assignments are more of a Ruby thing.
Info about array indexOf support.