Changes for shopping cart prototype:
-Fixed refreshing of items in cart after hitting back button
-"No items in cart" message is properly displayed after removing all items from cart
-Adding same item to cart multiple times is no longer possible
-"Add to Cart" link not visible for items that are already in cart
-Adding/removing items from cart redone
-Each Experiment has now a fixed price for testing purposes
-Added "Total Price" label into cart with final price for all articles in cart
Minor change for shopping cart creation