No way to get the etcd revision from puts and transaction transaction puts

[dementedhedgehog]

We want to check the whole etcd hasn't changed, for reasons... Would it be cool to return them instead of None, something like the following:

diff --git a/etcd3/client.py b/etcd3/client.py
index 662d125..55a85df 100644
--- a/etcd3/client.py
+++ b/etcd3/client.py
@@ -346,12 +346,13 @@ class Etcd3Client(object):
         :type lease: either :class:`.Lease`, or int (ID of lease)
         """
         put_request = self._build_put_request(key, value, lease=lease)
-        self.kvstub.Put(
+        meta_data = self.kvstub.Put(
             put_request,
             self.timeout,
             credentials=self.call_credentials,
             metadata=self.metadata
         )
+        return (True, meta_data)
 
     @_handle_errors
     def replace(self, key, initial_value, new_value):
@@ -644,7 +645,7 @@ class Etcd3Client(object):
         for response in txn_response.responses:
             response_type = response.WhichOneof('response')
             if response_type == 'response_put':
-                responses.append(None)
+                responses.append(response)
 
             elif response_type == 'response_range':
                 range_kvs = []