Log: Another step in the move from logfiles to priorities.

skygw_[enable|disable]_log has now been removed from the external
interface and priorities must instead be set using
mxs_log_set_priority_enabled(int priority, bool enabled). A bitmask
is already being updated, but internally and as used by the LOG_IF
macros, the actual enabling is still made using logfile ids.

The configuration entries have been replaced as follows:

	log_messages -> log_notice
	log_trace    -> log_info

The old ones can be used, but cause a warning to be logged.

Similarily the maxadmin commands have been updated.
"[enable|disable] log ..." works as expected, but there will be
a message about it being deprecated. Instead there is now a
[enable|disable] log-priority err|warning|notice|info|debug
command that should be used instead.

server/modules/routing/binlog/maxbinlogcheck.c

@@ -125,13 +125,8 @@ int main(int argc, char **argv) {
 	num_args = optind;
 
 	mxs_log_init(NULL, NULL, LOG_TARGET_DEFAULT);
-
 	mxs_log_set_augmentation(0);
-
-	if (!debug_out)
-		skygw_log_disable(LOGFILE_DEBUG);
-	else
-		skygw_log_enable(LOGFILE_DEBUG);
+	mxs_log_set_priority_enabled(LOG_DEBUG, debug_out);
 
 	if ((inst = calloc(1, sizeof(ROUTER_INSTANCE))) == NULL) {
 		LOGIF(LE, (skygw_log_write_flush(LOGFILE_ERROR,