CurrencyProviderSpi.getCurrencies should specify first criteria wins

[marschall]

CurrencyQuery allows to specify several criteria eg. currency codes and countries eg. "USD" and "es_EC"
However javax.money.spi.CurrencyProviderSpi#getCurrencies(CurrencyQuery) does not specify what happens when multiple criteria are set. JDKCurrencyProvider currently behaves like this:

1. If a currency code is specified search by currency code, otherwise
2. If a country is specified search by country, otherwise
3. If a numeric code is specified search by numeric code, otherwise
4. return everything