base: add PacketBase to provide wrappers for congestion tags

refs #3797

Change-Id: I8747bb4fcbc11bfd1731516896b8aef1ec181c36
diff --git a/src/interest.hpp b/src/interest.hpp
index 52cabf7..15a1501 100644
--- a/src/interest.hpp
+++ b/src/interest.hpp
@@ -24,8 +24,8 @@
 
 #include "delegation-list.hpp"
 #include "name.hpp"
+#include "packet-base.hpp"
 #include "selectors.hpp"
-#include "tag-host.hpp"
 #include "util/time.hpp"
 
 namespace ndn {
@@ -39,7 +39,7 @@
 
 /** @brief represents an Interest packet
  */
-class Interest : public TagHost, public enable_shared_from_this<Interest>
+class Interest : public PacketBase, public enable_shared_from_this<Interest>
 {
 public:
   class Error : public tlv::Error