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/face/ethernet-face.cpp b/daemon/face/ethernet-face.cpp
index e619724..66dcf08 100644
--- a/daemon/face/ethernet-face.cpp
+++ b/daemon/face/ethernet-face.cpp
@@ -5,6 +5,7 @@
  */
 
 #include "ethernet-face.hpp"
+#include "core/logger.hpp"
 #include "core/network-interface.hpp"
 
 #include <pcap/pcap.h>