Improve RGW config section
Improve RGW config section

Use hostname in socket and log.
Improve jinja template so when a var doesn't exist we don't indent the
next line.

Signed-off-by: Sébastien Han <c944cdd58d18a32bd34d661eafe66112d96c6cc1@enovance.com>

ceph/ansible-ceph-common