Restart Ceph service after a configuration change

After a change is made on the configuration file we must restart the
Ceph services. I also added a check that verifies if a socker exists
because during the first play there are no services running. We check if
a socket exists, if not we don't try to restart the services, if it
exists we can restart them.

Signed-off-by: Sébastien Han <sebastien.han@enovance.com>