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/stream-face.hpp b/daemon/face/stream-face.hpp
index a1aa7c1..1b5b124 100644
--- a/daemon/face/stream-face.hpp
+++ b/daemon/face/stream-face.hpp
@@ -9,6 +9,7 @@
 
 #include "face.hpp"
 #include "local-face.hpp"
+#include "core/logger.hpp"
 
 namespace nfd {