Cleanup iostream includes

Change-Id: I16dd945998463975b140c7a010d64a112f95d8ba
diff --git a/src/security/transform/stream-sink.hpp b/src/security/transform/stream-sink.hpp
index f384dc4..ae5d567 100644
--- a/src/security/transform/stream-sink.hpp
+++ b/src/security/transform/stream-sink.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2016 Regents of the University of California.
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,7 +23,6 @@
 #define NDN_CXX_SECURITY_TRANSFORM_STREAM_SINK_HPP
 
 #include "transform-base.hpp"
-#include <iostream>
 
 namespace ndn {
 namespace security {