notification: Dump loaded options during start up

... so that operators can review effective values (except for secret
information such as password) from the log.

The same was already implemented in polling agents but has never been
added to agent-notification yet.

Change-Id: I69be0229d7b692ee06fc406e3f15bac33f46ad54

ceilometer/cmd/agent_notification.py

@@ -16,13 +16,17 @@
 
 import cotyledon
 from cotyledon import oslo_config_glue
+from oslo_log import log
 
 from ceilometer import notification
 from ceilometer import service
 
+LOG = log.getLogger(__name__)
+
 
 def main():
     conf = service.prepare_service()
+    conf.log_opt_values(LOG, log.DEBUG)
 
     sm = cotyledon.ServiceManager()
     sm.add(notification.NotificationService,