net: move network-related files to src/net

Some namespaces are changed:

* ndn::util::FaceUri is now ndn::FaceUri
* ndn::util::ethernet is now ndn::ethernet
* ndn::util::NetworkMonitor and related classes are now in ndn::net

refs #3940

Change-Id: Ia4754caef9726efc73f5a303cec46fc95c744d70
diff --git a/src/net/detail/network-monitor-impl-noop.hpp b/src/net/detail/network-monitor-impl-noop.hpp
new file mode 100644
index 0000000..f0c5fb0
--- /dev/null
+++ b/src/net/detail/network-monitor-impl-noop.hpp
@@ -0,0 +1,61 @@
+/* -*- 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).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ *
+ * @author Davide Pesavento <davide.pesavento@lip6.fr>
+ */
+
+#ifndef NDN_NET_NETWORK_MONITOR_IMPL_NOOP_HPP
+#define NDN_NET_NETWORK_MONITOR_IMPL_NOOP_HPP
+
+#include "../network-monitor.hpp"
+
+namespace ndn {
+namespace net {
+
+class NetworkMonitor::Impl
+{
+public:
+  Impl(NetworkMonitor& nm, boost::asio::io_service& io)
+  {
+  }
+
+  uint32_t
+  getCapabilities() const
+  {
+    return NetworkMonitor::CAP_NONE;
+  }
+
+  shared_ptr<NetworkInterface>
+  getNetworkInterface(const std::string&) const
+  {
+    return {};
+  }
+
+  std::vector<shared_ptr<NetworkInterface>>
+  listNetworkInterfaces() const
+  {
+    return {};
+  }
+};
+
+} // namespace net
+} // namespace ndn
+
+#endif // NDN_NET_NETWORK_MONITOR_IMPL_NOOP_HPP