add lock messages

weed/pb/master.proto

@@ -314,6 +314,7 @@ message LeaseAdminTokenRequest {
   int64 previous_lock_time = 2;
   string lock_name = 3;
   string client_name = 4;
+  string message = 5;
 }
 message LeaseAdminTokenResponse {
   int64 token = 1;