acknowledge in ipay88 module does not work

[muhammadn]

The code below:

        def acknowledge
          secure? && (!success? || requery == "00")
        end

at:

https://github.com/Shopify/offsite_payments/blob/master/lib/offsite_payments/integrations/ipay88.rb

shouldn't it be:

        def acknowledge
          secure? && (success? || requery == "00")
        end

as the previous commiter set it as !success which i feel it is wrong.