lib: make NOTICE the default log level

I think notice is a good default - it should be used for scarce messages
that the user should see, while info level provides more low level info.

It could make sense to increase the log level to info if running with
journalctl (but it might be overkill).

lib/log.h

@@ -9,7 +9,7 @@
 #include "lib/defines.h"
 
 
-#define LOG_DEFAULT_LEVEL	LOG_WARNING
+#define LOG_DEFAULT_LEVEL	LOG_NOTICE
 
 /* Targets */