We don't call klog.InitFlags yet, because that will cause a flag
redefinition error until we get everyone to stop using glog. That
will happen when we update to k8s 1.13.
Because the primary use-case is S3-style stores, we haven't really used
directories. If we have a use-case, we can always pass a boolean
parameter or create an alternative function.
This lets us configure cross-project permissions while ourselves needing
minimal permissions, but also gives us a nice hook for future lockdown
of object-level permissions.