[config] Change sample disk folder back to /tmp
[config] Change sample disk folder back to /tmp

- it breaks Travis build due to hard coded local path

xephonhq/xephon-k,xephonhq/xephon-k,xephonhq/xephon-k,xephonhq/xephon-k,xephonhq/xephon-k,xephonhq/xephon-k