Fix default value

DependencyInjection/Configuration.php

@@ -88,13 +88,12 @@ class Configuration implements ConfigurationInterface
                             ->end()
                         ->end()
                         ->arrayNode('blocks')
-                            ->defaultValue(array(array('position' => 'left', 'type' => 'sonata.admin.block.admin_list')))
+                            ->defaultValue(array(array('position' => 'left', 'settings' => array(), 'type' => 'sonata.admin.block.admin_list')))
                             ->prototype('array')
                                 ->children()
                                     ->scalarNode('type')->cannotBeEmpty()->end()
                                     ->arrayNode('settings')
-                                        ->useAttributeAsKey('id')
-                                        ->prototype('scalar')->end()
+                                        ->prototype('scalar')->defaultValue(array())->end()
                                     ->end()
                                     ->scalarNode('position')->defaultValue('right')->end()
                                 ->end()