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>
Records: enhance Record API (WIP)
Uploader: first tasks version (WIP)
Uploader: first prototype of insert mode