src: Remove unnecessary uses of boost::cref in make_shared and replace boost::cref/boost::ref with just cref/ref

In some cases, due to argument-dependent lookup, it is necessary to use
ndn::ref, instead of just ref.

Change-Id: I682180a007609535855f77511b49622154ad4f11
Refs: #1591
diff --git a/common.hpp b/common.hpp
index 6e13c4e..c815bbc 100644
--- a/common.hpp
+++ b/common.hpp
@@ -46,7 +46,6 @@
 #include <boost/assert.hpp>
 #include <boost/lexical_cast.hpp>
 #include <boost/noncopyable.hpp>
-#include <boost/ref.hpp>
 #include <boost/scoped_ptr.hpp>
 
 namespace nfd {
@@ -63,6 +62,8 @@
 using ndn::const_pointer_cast;
 using ndn::function;
 using ndn::bind;
+using ndn::ref;
+using ndn::cref;
 
 using ndn::Interest;
 using ndn::Data;