Allow stash restore client to write to filesystem with NetApp .snapshot directory

Currently the restore client requires that the stash home directory be empty.

This requirement is problematic when the home directory is a NFS mounted NetApp volume/qtree where the volume has snapshots enabled, as it will contain a .snapshot directory.

The .snapshot directory can not be removed, it must be disabled by the storage administrator. But disabling snapshots also affects every other qtree on the volume.

For a recent restore, I had to have our storage admin temporarily disable snapshots. Even though the restore was brief, it turns out that there were users that needed to access their .snapshot directory during that time.