fix(marked-for-desk): make user optional
fix(marked-for-desk): make user optional

so we can mark items on ingest via macro

SDANSA-38

ioanpocol/superdesk-core,superdesk/superdesk-core,ioanpocol/superdesk-core,superdesk/superdesk-core,petrjasek/superdesk-core,superdesk/superdesk-core,mugurrus/superdesk-core,superdesk/superdesk-core,petrjasek/superdesk-core,mugurrus/superdesk-core,petrjasek/superdesk-core,mdhaman/superdesk-core,mdhaman/superdesk-core,petrjasek/superdesk-core,mugurrus/superdesk-core,ioanpocol/superdesk-core,mdhaman/superdesk-core