Add `extension` column property to StoredFileMixin
Add `extension` column property to StoredFileMixin

indico/indico,DirkHoffmann/indico,pferreir/indico,indico/indico,ThiefMaster/indico,DirkHoffmann/indico,pferreir/indico,pferreir/indico,ThiefMaster/indico,ThiefMaster/indico,indico/indico,pferreir/indico,DirkHoffmann/indico,ThiefMaster/indico,indico/indico,DirkHoffmann/indico