Fixed several issues to get everything to work with product class.

* Set the first product object to 1 to prevent error where zero
couldn’t be passed to the cart class.
* Randomized product id to reinforce that the product id does not equal
the product object key
* Modified the table creation to be easier to understand
* Moved money_format function to the cart class
* Moved $_Session functions to the cart class
* Changed the posted value to the product object key to correct the
data retrieval
* Changed the $total property to $grandtotal
* Changed the $_Session name from ‘items’ to ‘cart’
* Used the unset command where it was more appropriate in the
removeItemFromCart and clearCart methods