Make kea-lfc output to cout when not called from Kea
kea-lfc does not have an enabled logger when called standalone. This means it never outputs anything. This makes debugging problems a challenge. Let's detect this situation programatically and make it output to cout and cerr in that situation. We could create a CoutLogger that works with the usual LOG_*()
macros. Useful if there are more cases like this i.e. more binaries.