Increase rabbitmq connections attempt

Workers instantly exit if rabbitmq server is not available. This changes
use connection_attemps and retry_delay pika connection parameters to try to
reconnect before failing.

Change-Id: I00ff950270360405da092803c1d251552c837831

etc/storyboard.conf.sample

@@ -107,6 +107,12 @@ lock_path = $state_path/lock
 # The name of the queue that will be created for API events.
 # rabbit_event_queue_name=storyboard_events
 
+# The number of connection attempts before giving-up
+# rabbit_connection_attempts = 6
+
+# The interval between connection attempts (in seconds)
+# rabbit_retry_delay = 10
+
 [database]
 # This line MUST be changed to actually run storyboard
 # Example:

storyboard/notifications/conf.py

@@ -40,4 +40,8 @@ NOTIFICATION_OPTS = [
     cfg.StrOpt("rabbit_virtual_host", default="/",
                help="The virtual host within which our queues and exchanges "
                     "live."),
+    cfg.IntOpt("rabbit_connection_attempts", default=6,
+               help="The number of connection attempts before giving-up"),
+    cfg.IntOpt("rabbit_retry_delay", default=10,
+               help="The interval between connection attempts (in seconds)")
 ]

storyboard/notifications/connection_service.py

@@ -56,7 +56,9 @@ class ConnectionService(object):
             conf.rabbit_host,
             conf.rabbit_port,
             conf.rabbit_virtual_host,
-            self._connection_credentials)
+            self._connection_credentials,
+            connection_attempts=conf.rabbit_connection_attempts,
+            retry_delay=conf.rabbit_retry_delay)
 
     def _connect(self):
         """This method connects to RabbitMQ, establishes a channel, declares