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

daemon/table/cs-entry.cpp

@@ -7,6 +7,7 @@
  */
 
 #include "cs-entry.hpp"
+#include "core/logger.hpp"
 
 namespace nfd {
 namespace cs {