jsonalchemy: enhance default value search

• Additionally to setting the default value, the meta-metadata for the field is guessed from the field definitions following this rule order: creator, derived, calculated. If none of them is found every meta-metadad field is set to UNKNOWN.

• Convenience property additional_info added to SmartJson

Signed-off-by: Esteban J. G. Gabancho <egabancho@gmail.com>