src: Refactoring common.hpp and minimizing exposed includes

Face class has relatively large rewrite to hide internals using
Implementor pattern.  As of this commit, <boost/asio.hpp> is not
automatically included whenever ndn-cxx/face.hpp is included.  If it is
needed to directly work with io_service, asio.hpp should be specifically
included.

Change-Id: Ie742b851025b4e3da634eb981319df0f42937855
diff --git a/tests/security/test-sec-tpm-file.cpp b/tests/security/test-sec-tpm-file.cpp
index 05f1afc..191764e 100644
--- a/tests/security/test-sec-tpm-file.cpp
+++ b/tests/security/test-sec-tpm-file.cpp
@@ -16,6 +16,8 @@
 
 #include "util/time.hpp"
 
+#include <boost/lexical_cast.hpp>
+
 #include "boost-test.hpp"
 
 using namespace std;