FlexOfferCurrencyValidator not included in the default Spring configuration

[tomwetjens]

Describe the bug
FlexOfferCurrencyValidator not included in the default Spring configuration

To Reproduce
Use the Shapeshifter library with a Spring application using the default configuration.
Call UftpValidationService to validate a FlexOffer with an invalid Currency.

FlexOfferCurrencyValidator is not called at all, thus Currency is not validated.

Expected behavior
Currency is validated and considered 'not valid' leading to the FlexOrder being rejected.

FlexOfferCurrencyValidator must be added to ShapeshifterConfiguration#uftpValidationService