Add new configuration property.

src/Bundle/ChillMainBundle/DependencyInjection/Configuration.php

@@ -41,6 +41,10 @@ class Configuration implements ConfigurationInterface
 
         $rootNode
             ->children()
+            ->scalarNode('phonenumber_default_country_code')
+            ->cannotBeEmpty()
+            ->defaultValue('+32')
+            ->end() // end of scalar 'phonenumber_default_country_code'
             ->scalarNode('installation_name')
             ->cannotBeEmpty()
             ->defaultValue('Chill')