Revise python save load api using new load/save op (#7995)

* initial commit

* add get_parameters method

* add get_parameters method

* small fix

* address comments

* address comments

* address comments

* fix

python/paddle/v2/fluid/framework.py

@@ -489,7 +489,8 @@ class Operator(object):
         no_kernel_op_set = {
             'feed', 'fetch', 'save', 'load', 'recurrent',
             'rnn_memory_helper_grad', 'conditional_block', 'while', 'send',
-            'recv', 'listen_and_serv', 'parallel_do'
+            'recv', 'listen_and_serv', 'parallel_do', 'save_combine',
+            'load_combine'
         }
         if type not in no_kernel_op_set:
             self.desc.infer_var_type(self.block.desc)