Merge pull request #97 from mhujer/symfony42

Fix deprecation for symfony/config 4.2

Author: Sam Partington

DependencyInjection/Configuration.php

@@ -14,8 +14,14 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root("white_october_breadcrumbs");
+        $treeBuilder = new TreeBuilder("white_october_breadcrumbs");
+
+        if (method_exists($treeBuilder, 'getRootNode')) {
+            $rootNode = $treeBuilder->getRootNode();
+        } else {
+            // BC layer for symfony/config 4.1 and older
+            $rootNode = $treeBuilder->root("white_october_breadcrumbs");
+        }
 
         $rootNode->
             children()->