core: drop std::function and ndn::Exclude from common.hpp, add ndn::optional

Change-Id: Ie3983d8b6f9929430efd8ada8d942e3f95755cd4
diff --git a/tools/nfdc/module.hpp b/tools/nfdc/module.hpp
index 765e39b..b8ede30 100644
--- a/tools/nfdc/module.hpp
+++ b/tools/nfdc/module.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2017,  Regents of the University of California,
+ * Copyright (c) 2014-2018,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -55,7 +55,7 @@
    */
   virtual void
   fetchStatus(Controller& controller,
-              const function<void()>& onSuccess,
+              const std::function<void()>& onSuccess,
               const Controller::DatasetFailCallback& onFailure,
               const CommandOptions& options) = 0;