when we set rancher.debug to true, the current code also set `-D` flag
to system-docker and user-docker daemon.
and then we change rancher.debug to false, the `-D` flag is also exist
by using command `sudo ros config get rancher.docker`.
this patch fix it.
Signed-off-by: Wang Long <long.wanglong@huawei.com>
Read files cloud-config.d in alphanumeric order, then cloud-config.yml
`ros config` writes to cloud-config.yml (and cloud-config.d/private.yml - only private keys)
Add (c *CloudConfig) Save() method, use it to save the changed config
Read and apply metadata as part of LoadConfig()
Simplify ros config export logic
