Cleanup iostream includes

Change-Id: I16dd945998463975b140c7a010d64a112f95d8ba
diff --git a/tests/unit-tests/util/io.t.cpp b/tests/unit-tests/util/io.t.cpp
index 20e9412..b2ec66b 100644
--- a/tests/unit-tests/util/io.t.cpp
+++ b/tests/unit-tests/util/io.t.cpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -23,8 +23,8 @@
 
 #include "boost-test.hpp"
 #include "identity-management-fixture.hpp"
+
 #include <boost/filesystem.hpp>
-#include <fstream>
 
 namespace ndn {
 namespace tests {