Merge pull request #12 from bookboon/hotfix/root-node

Use TreeBuilder constructor, deprecated using RootNode

Author: lkm

DependencyInjection/Configuration.php

@@ -15,10 +15,11 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('bookboonapi');
+        $treeBuilder = new TreeBuilder('bookboonapi');
 
-        $rootNode->children()
+        $treeBuilder
+            ->getRootNode()
+            ->children()
             ->scalarNode('id')->isRequired()->end()
             ->scalarNode('secret')->isRequired()->end()
             ->scalarNode('branding')->end()
@@ -36,4 +37,4 @@ public function getConfigTreeBuilder()
 
         return $treeBuilder;
     }
-}
+}