Consistent Output for SS messages

[mjbrunelle]

Please bring uniformity to the output from [-- ShopSiteMessages --]

Example:

Message: "You can not Checkout since there are no items in your cart." has no alignment tag surrounding the output table.

Message: "This store has a minimum order amount. In order to checkout it must be met." has a depricated tag <center></center> surrounding the output table.

Please do not take for granted we want to center the output, just put it out with a class so we can format ourselves.

MarkB