Show transaction Id in payment info

This fixes last transaction id in `Payment Info' section.

Payment Information
Payment by card: Visa, Mastercard
Transaction ID:	xxxxx-yyyyy
Order was placed using USD

Note: since Mage_Ecomcharge_Block_Standard_Info block is used both for admin and customer area,
transaction id is displayed in customer area while viewing order/invoice and printable version of order/invoice