Fix case where args or kwargs are not specified

Currently, the m_ret line will error if the loop state definition does not specify values for args or kwargs, because None is neither iterable nor a map. If not specified, those values should be set to an empty list and empty dict.

salt/states/loop.py

@@ -94,7 +94,11 @@ def until(name,
         ret['comment'] = 'The execution module {0} will be run'.format(name)
         ret['result'] = None
         return ret
-
+    if not m_args:
+        m_args = []
+    if not m_kwargs:
+        m_kwargs = {}
+
     def timed_out():
         if time.time() >= timeout:
             return True