deposit: author's field validation

* Field's validation reorganization.

* Adds custom validation to author's fields.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
deposit: lazy string types workaround

* Hotfix for language field.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
deposit: hotfix for empty author's dynamic field

* By default, even if the author's field is empty its value is [{}],
  which does not appear empty. The empty values should be cleared
  before processing the author's field.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
base: Invenio bundle name adaptation

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
deposit: workflow comment added

* Adds commented out upload_record_sip() task for developers to
  upload locally the form as MarcXML.

* Clean up imports.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>