Log: add level "DEFAULT"

Map LogLevel::INFO to G_LOG_LEVEL_INFO, and LogLevel::DEFAULT to
G_LOG_LEVEL_MESSAGE.  Now client connect/disconnect message are only
logged on log_level "secure".

src/UpdateContainer.cxx

@@ -112,8 +112,8 @@ update_container_file(Directory &directory,
 
 		modified = true;
 
-		FormatInfo(update_domain, "added %s/%s",
-			   directory.GetPath(), vtrack);
+		FormatDefault(update_domain, "added %s/%s",
+			      directory.GetPath(), vtrack);
 		g_free(vtrack);
 	}