WebDeposit: configuration file and MARCXML export

• Introduces webdeposit configuration file that overrides the default behaviour of forms and fields. The admin can define a dictionary so that the functionality (autocompletion, validation, labels, widgets etc) changes accodring to the deposition and form the user is browsing.

• Introduces WebDepositForm, a generic form to be inherited by all deposition forms. Used to load all configuration for the form and fields from the config file.

• Adds support for multiple validators.

• Adds new workflow functions export_marc_from_json and create_record_from_marc.

• Adds new file cook json utils containing json transformation functions.

• Introduces new WebDepositForm.

• Adds cook_json function to config file.

• Adds cook_json function to WebDepositForm and WebDepositField.

• Removes WebDeposit workflow table.

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>