Send office files with attachment disposition
Send office files with attachment disposition

fixes #1519

OmeGak/indico,indico/indico,ThiefMaster/indico,mic4ael/indico,pferreir/indico,mvidalgarcia/indico,pferreir/indico,mic4ael/indico,ThiefMaster/indico,DirkHoffmann/indico,pferreir/indico,mic4ael/indico,pferreir/indico,OmeGak/indico,DirkHoffmann/indico,DirkHoffmann/indico,OmeGak/indico,mvidalgarcia/indico,mvidalgarcia/indico,indico/indico,ThiefMaster/indico,indico/indico,indico/indico,ThiefMaster/indico,mic4ael/indico,OmeGak/indico,DirkHoffmann/indico,mvidalgarcia/indico