added validation 'mandatory_in_dictionary'
added validation 'mandatory_in_dictionary'

In content types mandatory_in_dictionary validation can be defined:
"mandatory_in_dictionary": [key, key...]

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