No usable constructor for java.util.Currency

[umbreak]

org.mongodb.morphia.mapping.MappingException: No usable constructor for java.util.Currency

Currency usses a factory method to create an instance of the object, and does not provide any constructor. Can you provide a mapping for it? Or I have to write my own converter?

Note that jackson and other JSON libraries do the marshalling/unmarshalling of Currency correctly and out of the box.

[evanchooly]

This can be handled by writing a converter. Bumping to post-1.0 for now unless a converter is submitted.

[evanchooly]

depends on #940