Support to upload multiple files when creating a new ticket and scan them
    
    With this commit we can select multiple files when creating a new ticket
    they will get uploaded and inserted into the content of the ticket as
    expected.
    We also fix scanning these attachments for Virus if this option is
    enabled.
    
    Fixes https://pagure.io/pagure/issue/2366
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>