Port statement voucher killer patch

In the module voucher killer ,
 when it import payment line into the bank statement it takes the maturity date of the payment line,
to define the bank statement line date, that is wrong it must take the date of the payment line or if not present the date of the payment order.

See bug : https://bugs.launchpad.net/banking-addons/+bug/1301781
The date should not be fixed because it will fail next year (no period). You should use:

    date: !eval time.strftime('%Y-12-20')