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/face.cpp b/src/face.cpp
index c77d3e0..1521788 100644
--- a/src/face.cpp
+++ b/src/face.cpp
@@ -23,10 +23,10 @@
 #include "detail/face-impl.hpp"
 
 #include "encoding/tlv.hpp"
+#include "net/face-uri.hpp"
 #include "security/signing-helpers.hpp"
 #include "util/time.hpp"
 #include "util/random.hpp"
-#include "util/face-uri.hpp"
 
 // A callback scheduled through io.post and io.dispatch may be invoked after the face
 // is destructed. To prevent this situation, these macros captures Face::m_impl as weak_ptr,
@@ -117,7 +117,7 @@
 
   std::string protocol;
   try {
-    util::FaceUri uri(transportUri);
+    FaceUri uri(transportUri);
     protocol = uri.getScheme();
 
     if (protocol == "unix") {
@@ -133,7 +133,7 @@
   catch (const Transport::Error& error) {
     BOOST_THROW_EXCEPTION(ConfigFile::Error(error.what()));
   }
-  catch (const util::FaceUri::Error& error) {
+  catch (const FaceUri::Error& error) {
     BOOST_THROW_EXCEPTION(ConfigFile::Error(error.what()));
   }
 }