Update ProductPage to utilize product hashing

Add _config/config.yml
Update FoxyCart.php to access StoreKey and StoreName from SiteConfig
Update validation of add to cart fields
Update foxycart.cart_validation.php to latest version and access keys by getters
Update ProductPage.php to encrypt add to cart form using FoxyCart encryption
Merge pull request #13 from nhorstmeier/FoxyCartValidation

Update ProductPage to utilize product hashing