rename DI extension to fix bundle registration in Symfony

src/DependencyInjection/ImageExtension.php → src/DependencyInjection/ImagingExtension.php

@@ -14,7 +14,7 @@
  *
  * To learn more see {@link http://symfony.com/doc/current/cookbook/bundles/extension.html}
  */
-class ImageExtension extends Extension
+class ImagingExtension extends Extension
 {
     /**
      * {@inheritDoc}