Native binary uuid support

[denny-bee]

Many people out there recommend storing uuids as binary. There are some archived packages which are trying to workaround and are not optimal, because they seem to work, but come with many other problems.
Maybe there could be a way to declare two extra methods for custom casts which are used for writing and retrieving data from the database.
This native handling would be way better then some workarounds of the orm.