Show path on template and manage folder pages

So the page headings stay consistent as you click around, and make it
easy to get back where you came from.

tests/__init__.py

@@ -229,6 +229,7 @@ def template_json(service_id,
         'reply_to': reply_to,
         'reply_to_text': reply_to_text,
         'is_precompiled_letter': is_precompiled_letter,
+        'folder': None,
     }
     if content is None:
         template['content'] = "template content"