minor #141 Adapt to the new structure (greg0ire)

This PR was merged into the 2.1.x-dev branch.

Discussion
----------

Adapt to the new structure

Use class detection to determine what the most sensible defaults are, so
that this extension requires even less configuration.
Fixes #140

Commits
-------

fd82f9e Adapt to the new structure

doc/index.rst

@@ -211,8 +211,9 @@ configure Symfony2 kernel inside Behat to fulfil all your needs.
     or a path relative to the Behat configuration file. Defaults to ``app/autoload.php``.
   - ``path`` - defines the path to the kernel class file in order to instantiate it. It
     can be an absolute path or a path relative to the Behat configuration file. Defaults
-    to ``app/AppKernel.php``.
-  - ``class`` - defines the name of the kernel class. Defaults to ``AppKernel``.
+    to ``app/AppKernel.php`` or ``src/Kernel.php``, whichever exists.
+  - ``class`` - defines the name of the kernel class. Defaults to
+    ``AppKernel`` or ``App\Kernel``, whichever exists.
   - ``env`` - defines the environment in which kernel should be instantiated and used
     inside suite. Defaults to ``test``.
   - ``debug`` - defines whether kernel should be instantiated with ``debug`` option

src/Behat/Symfony2Extension/ServiceContainer/Symfony2Extension.php

@@ -71,9 +71,9 @@ public function configure(ArrayNodeDefinition $builder)
                 ->arrayNode('kernel')
                     ->addDefaultsIfNotSet()
                     ->children()
-                        ->scalarNode('bootstrap')->defaultValue(self::DEFAULT_KERNEL_BOOTSTRAP)->end()
-                        ->scalarNode('path')->defaultValue('app/AppKernel.php')->end()
-                        ->scalarNode('class')->defaultValue('AppKernel')->end()
+                        ->scalarNode('bootstrap')->defaultValue(class_exists('App\Kernel') ? null : self::DEFAULT_KERNEL_BOOTSTRAP)->end()
+                        ->scalarNode('path')->defaultValue(class_exists('App\Kernel') ? null : 'app/AppKernel.php')->end()
+                        ->scalarNode('class')->defaultValue(class_exists('App\Kernel') ? 'App\Kernel' : 'AppKernel')->end()
                         ->scalarNode('env')->defaultValue('test')->end()
                         ->booleanNode('debug')
                             ->beforeNormalization()