[Templating] fixed cache loader as the logical name can contain characters not valid on some OSes

src/Symfony/Component/Templating/Loader/CacheLoader.php

@@ -50,7 +50,7 @@ class CacheLoader extends Loader
      */
     public function load(TemplateReferenceInterface $template)
     {
-        $key = $template->getLogicalName();
+        $key = md5($template->getLogicalName());
         $dir = $this->dir.DIRECTORY_SEPARATOR.substr($key, 0, 2);
         $file = substr($key, 2).'.tpl';
         $path = $dir.DIRECTORY_SEPARATOR.$file;