Load rabbitmq_federation plugin first

Currently the 'rabbitmq-plguins enable' command does not explicitly
enable the plugin if that is implicitly enabled in CentOS. This change
let the rabbitmq_federation plugin loaded before its management plugin
to workaround the problem.

spec/acceptance/parameter_spec.rb

@@ -16,7 +16,7 @@ class { 'rabbitmq':
  admin_enable => true,
  }
 
- rabbitmq_plugin { [ 'rabbitmq_federation_management', 'rabbitmq_federation' ]:
+ rabbitmq_plugin { [ 'rabbitmq_federation', 'rabbitmq_federation_management' ]:
  ensure => present
  } ~> Service['rabbitmq-server']