Update Configuration.php

Author: dquerioux

DependencyInjection/Configuration.php

@@ -293,6 +293,7 @@ public function getConfigTreeBuilder()
                             ->scalarNode('priority')->defaultValue(0)->end()
                             ->scalarNode('level')->defaultValue('DEBUG')->end()
                             ->booleanNode('bubble')->defaultTrue()->end()
+                            ->scalarNode('app_name')->defaultValue(null)->end()
                             ->booleanNode('include_stacktraces')->defaultFalse()->end()
                             ->scalarNode('path')->defaultValue('%kernel.logs_dir%/%kernel.environment%.log')->end() // stream and rotating
                             ->scalarNode('file_permission')  // stream and rotating