management: ensure Element::Error inherits from tlv::Error

Add static asserts to ensure ndn::nfd::*::Error are subclasses of tlv::Error.

Add WireEncodable and WireDecodable concept checks to
ndn::nfd::* classes that represent TLV abstraction.

Move definition of ChannelStatus, FibEntry, ForwarderStatus,
StrategyChoice methods into .cpp.

Move declaration of FaceScope, FacePersistency, LinkType
into encoding/nfd-constants.hpp.

Eliminate duplicate RibFlags declaration.

refs #1983

Change-Id: I207bae479aa6da54a581a7cca5b2a13743827ff0
diff --git a/src/management/nfd-face-status.cpp b/src/management/nfd-face-status.cpp
index 17145bd..8a08825 100644
--- a/src/management/nfd-face-status.cpp
+++ b/src/management/nfd-face-status.cpp
@@ -20,13 +20,21 @@
  */
 
 #include "nfd-face-status.hpp"
+#include "encoding/tlv-nfd.hpp"
+#include "encoding/block-helpers.hpp"
+#include "util/concepts.hpp"
 
 namespace ndn {
 namespace nfd {
 
+//BOOST_CONCEPT_ASSERT((boost::EqualityComparable<FaceStatus>));
+BOOST_CONCEPT_ASSERT((WireEncodable<FaceStatus>));
+BOOST_CONCEPT_ASSERT((WireDecodable<FaceStatus>));
+static_assert(std::is_base_of<tlv::Error, FaceStatus::Error>::value,
+              "FaceStatus::Error must inherit from tlv::Error");
+
 FaceStatus::FaceStatus()
-  : FaceTraits()
-  , m_hasExpirationPeriod(false)
+  : m_hasExpirationPeriod(false)
   , m_nInInterests(0)
   , m_nInDatas(0)
   , m_nOutInterests(0)