fix(content types): Fix the issue on prepopulation of content type re: custom fields
fix(content types): Fix the issue on prepopulation of content type re: custom fields

On prepopulation if we have a custom_subject defined in editor, because
of default values it will be added also subject.
The default values should be applied only if editor and schema are not
set at all.

ioanpocol/superdesk-core,hlmnrmr/superdesk-core,mdhaman/superdesk-core,petrjasek/superdesk-core,ancafarcas/superdesk-core,hlmnrmr/superdesk-core,superdesk/superdesk-core,petrjasek/superdesk-core,superdesk/superdesk-core,ioanpocol/superdesk-core,mugurrus/superdesk-core,mdhaman/superdesk-core,superdesk/superdesk-core,ancafarcas/superdesk-core,marwoodandrew/superdesk-core,petrjasek/superdesk-core,superdesk/superdesk-core,nistormihai/superdesk-core,mugurrus/superdesk-core,nistormihai/superdesk-core,mdhaman/superdesk-core,ioanpocol/superdesk-core,mugurrus/superdesk-core,marwoodandrew/superdesk-core,petrjasek/superdesk-core