Fix missing cotyledon options

The cotyledon library provides a few options to tune service behavior
(such as greceful_shutdown_timeout). Make sure these are added to
the generated config file.

Change-Id: I876d10879ad9906f3a6259b878af25c5a058c8ca
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

etc/ceilometer/ceilometer-config-generator.conf

@@ -3,6 +3,7 @@ output_file = etc/ceilometer/ceilometer.conf
 wrap_width = 79
 namespace = ceilometer
 namespace = ceilometer-auth
+namespace = cotyledon
 namespace = oslo.cache
 namespace = oslo.concurrency
 namespace = oslo.log