Ceph-deploy

In http://docs.ceph.com/docs/hammer/rados/operations/add-or-rm-mons/, for the final step, we tell the user to run "/usr/bin/ceph-mon" directly, instead of starting it through the init system like everything else.

When we tell users to start /usr/bin/ceph-mon outside the init system, we hit weird bugs where the init system interacts poorly with a daemon process that is running outside of it. It will be even worse with SELinux, or when Ceph runs as an unprivileged "ceph" UID.

We should change the instructions (and ceph-deploy) to use the init system, and run something like "service ceph start <monitor>" instead (or the systemd equivalent...).