fix drag&drop for pdfs from scanpix (#4054)
fix drag&drop for pdfs from scanpix (#4054)

when the item mimetype was application/pdf it didn't
add application/superdesk.item.* mimetype payload to
the event

SDNTB-747
superdesk/superdesk-client-core,petrjasek/superdesk-client-core,superdesk/superdesk-client-core,superdesk/superdesk-client-core,petrjasek/superdesk-client-core,petrjasek/superdesk-client-core,petrjasek/superdesk-client-core,superdesk/superdesk-client-core,petrjasek/superdesk-client-core,superdesk/superdesk-client-core