Fix incorrect initialization of buildout download API

This fixes a regression in commit 0f8a8b27
("default: bring some of the jinja2 improvements by refactoring the 2 recipes").

slapos/recipe/template/__init__.py

@@ -100,7 +100,7 @@ class Recipe(object):
 
     def _read(self, url, *args):
         path, is_temp = zc.buildout.download.Download(
-            self.buildout, hash_name=True,
+            self.buildout['buildout'], hash_name=True,
             )(url, self.md5sum or None)
         try:
             with open(path, *args) as f: