When using experimental feature "newstore", we save and load devices
information from `persist.json` instead of `devices.json`, in such case,
file `devices.json` isn't needed anymore, so remove it.
Signed-off-by: Wei Zhang <zhangwei555@huawei.com>
Fixes#803
The disk persist data should be "versioned" and baselined, any modification in
persist data should be considered potential break of backward compatibility.
Signed-off-by: Wei Zhang <zhangwei555@huawei.com>
