Fix a couple packaging problems (#656570, #783788)
    
    As per https://fedoraproject.org/wiki/Features/var-run-tmpfs,
    /var/cache/davfs2 and /var/run/mount.davfs should be marked %ghost.
    
    Also, the "duplicate" config files in /usr/share/davfs2 were actually
    used as templates for local configuration. My mistake!