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/mgmt/command-validator.cpp b/daemon/mgmt/command-validator.cpp
index fd8a124..eb76572 100644
--- a/daemon/mgmt/command-validator.cpp
+++ b/daemon/mgmt/command-validator.cpp
@@ -5,6 +5,8 @@
  */
 
 #include "command-validator.hpp"
+#include "core/logger.hpp"
+
 #include <ndn-cpp-dev/util/io.hpp>
 #include <ndn-cpp-dev/security/identity-certificate.hpp>
 
@@ -178,4 +180,3 @@
 }
 
 } // namespace nfd
-