Resolve "Revisit demos (formerly called examples) and update them"

Closes #209 (closed)

demos/demo_wolf_logging.cpp

-/**
- * \file test_wolf_logging.cpp
- *
- * Created on: Oct 28, 2016
- * \author: Jeremie Deray
- */
-
-#include "core/common/wolf.h"
-#include "core/utils/logging.h"
-
-int main(int, char*[])
-{
-  WOLF_INFO("test info ", 5, " ", 0.123);
-
-  WOLF_WARN("test warn ", 5, " ", 0.123);
-
-  WOLF_ERROR("test error ", 5, " ", 0.123);
-
-  WOLF_TRACE("test trace ", 5, " ", 0.123);
-
-  WOLF_DEBUG("test debug ", 5, " ", 0.123);
-
-  return 0;
-}