core: change logging from environment variable to configuration file-based

GlobalConfigurationFixture uses unit-tests.conf to determine default
and module specific logging levels. Logging will gracefully default to
INFO if unit-tests.conf is not found. See unit-tests.conf.sample for a
sample configuration file.

refs: #1375, #1267

Change-Id: Ib0c4eb4149748e6658f94ef1afa23ddd3072c0fa
diff --git a/daemon/common.hpp b/daemon/common.hpp
index 32ad4a4..76a553d 100644
--- a/daemon/common.hpp
+++ b/daemon/common.hpp
@@ -33,6 +33,8 @@
 #include <boost/asio.hpp>
 #include <boost/assert.hpp>
 #include <boost/functional/hash.hpp>
+#include <boost/algorithm/string.hpp>
+#include <boost/lexical_cast.hpp>
 
 #include <vector>
 #include <list>
@@ -44,8 +46,6 @@
 #include <algorithm>
 #include <numeric>
 
-#include "core/logger.hpp"
-
 namespace nfd {
 
 using boost::noncopyable;