Missing sanity check: user "cephadm" must exist on all minions that have cephadm role

[smithfarm]

Although the act of installing the cephadm package can be expected to create the cephadm user, this does not give us 100% certitude that the cephadm user will exist on all nodes where we expect it to. Users might delete the cephadm user, for example.

[ricardoasmarques]

This can only happen on ceph-salt status, because on ceph-salt apply/update/reboot the cephadm user will be recreated.

Relates to #379

[ricardoasmarques]

Note that ceph-salt explicitly creates the cephadm user [1], which means it will be recreated, if needed, everytime cephadm apply is executed.`

I don't see a reason to add this check, so I'm now closing the issue.

Feel free to reopen it if I'm missing something.

[1] https://github.com/ceph/ceph-salt/blob/master/ceph-salt-formula/salt/ceph-salt/common/sshkey.sls#L9-L15