Currency code should be configurable wherever currencies are specified (i.e. cost, price)

[jmiranda]

Consider defining a new domain called Money or Currency (with an amount and currency code) and use the GORM's embedded feature. Might need to make this a Groovy class and not a Grails domain class since it'll keep getting picked up by Liquibase when doing data model diffs. Just not sure if GORM allows for embedded properties to be POGOs.