Fix authentication in RabbitMQ (hopefully)

Signed-off-by: Aurélien Bompard <aurelien@bompard.org>

roles/rabbitmq_cluster/templates/rabbitmq.conf.j2

@@ -28,6 +28,7 @@ ssl_options.fail_if_no_peer_cert = true
 ssl_options.cacertfile           = /etc/rabbitmq/ca.crt
 ssl_options.certfile             = /etc/rabbitmq/nodecert/node.crt
 ssl_options.keyfile              = /etc/rabbitmq/nodecert/node.key
+ssl_cert_login_from              = common_name
 
 ## Authentication
 ##