Add __permissions__ attr to the handlers wrapped by the permissions decorator (#389)

So that, on import, we can easily figure out what permissions an endpoint might need

Author: Theodlz

app/access.py

@@ -75,6 +75,7 @@ def wrapper(self, *args, **kwargs):
                 raise tornado.web.HTTPError(401)
             return method(self, *args, **kwargs)
 
+        wrapper.__permissions__ = acl_list
         return wrapper
 
     return check_acls