data: Implementing FinalBlockId in Data packet's MetaInfo section

Change-Id: I4768aa0d7465f498b220910269db5e2aa69bbe51
diff --git a/src/encoding/block.hpp b/src/encoding/block.hpp
index 32523a5..2afd154 100644
--- a/src/encoding/block.hpp
+++ b/src/encoding/block.hpp
@@ -375,18 +375,12 @@
 inline Buffer::const_iterator
 Block::value_begin() const
 {
-  if (!hasValue())
-      throw Error("(Block::value_begin) Underlying value buffer is empty");
-
   return m_value_begin;
 }
 
 inline Buffer::const_iterator
 Block::value_end() const
 {
-  if (!hasValue())
-      throw Error("(Block::value_end) Underlying value buffer is empty");
-
   return m_value_end;
 }
 
diff --git a/src/encoding/tlv.hpp b/src/encoding/tlv.hpp
index 1ea0936..890ea84 100644
--- a/src/encoding/tlv.hpp
+++ b/src/encoding/tlv.hpp
@@ -49,6 +49,7 @@
   SignatureType = 22,
   KeyLocator    = 23,
   KeyLocatorDigest = 24,
+  FinalBlockId  = 25,
 
   AppPrivateBlock1 = 128,
   AppPrivateBlock2 = 32767