Fix #145, add authenticator role to tutorials

tutorials/tut1.rst

@@ -16,7 +16,7 @@ The previous tutorial created a :code:`web_anon` role in the database with which
   -- in the previous tutorial
 
   create role todo_user nologin;
-  grant todo_user to postgres;
+  grant todo_user to authenticator;
 
   grant usage on schema api to todo_user;
   grant all on api.todos to todo_user;