Refund amount sent to Solidus is floor of actual value

[simonpfry]

Currently if you refund through the Adyen admin (rather than from Solidus) when it receives a refund notification it creates a refund, but loses any of the 'cents' of the refund value, leading to small value mismatches between the refund amount and the order value.

#<AdyenNotification id: 11044, live: true, event_code: "REFUND", psp_reference: "1414520055394734", original_reference: "1714498686723596", merchant_reference: "R096559451", merchant_account_code: "LostmynameNAME081", event_date: "2016-01-05 14:52:19", success: true, payment_method: "directEbanking", operations: nil, reason: nil, currency: "EUR", value: 540, processed: true, created_at: "2016-01-05 14:53:15", updated_at: "2016-01-05 14:53:16", additional_data_alias_type: nil, additional_data_alias: nil>