The fileStore itself is aware that it's insecure, so we can make it
responsible for printing the warning. It's not "perfect", as we use
`os.Stderr` unconditionally (not `dockerCli.Err()`), but probably won't
make a difference in _most_ cases.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
ab80ea355f