Improve Google Checkout flow by altering the API request

Google Checkout does not automatically redirect back to the civiCRM site. Also, by default it seems to wait for us to indicate that we have "shipped" It seems that the digital delivery codes for their API: http://code.google.com/apis/checkout/developer/Google_Checkout_Digital_Delivery.html would go along way to solving both of these problems.

If we coded our requests for description based delivery, we could make the description something like: Click here to return to Organization Name to complete your purchase.

This would communicate to Google that we are not shipping anything and help direct the person back to the thank you screen.