Merge branch 'dnssec-cron-slaveblock' into 'stable-3.1'

DNSSEC-Cronjob should only run on ispconfig master as we are working with datalo…

…g and not accessing things directly

@tbrehm, am I right that `$app->db->datalogUpdate`for a soa on the ispc master does also update the dns_soa table in master database or do I have to do this by hand?
This could probably be a reason for the issue of @jnorell in #1491 ...

See merge request !446

Author: Till Brehm

server/lib/classes/cron.d/550-bind_dnssec.inc.php

@@ -28,7 +28,7 @@
 EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
-DNSSEC-Implementation by Alexander Täffner aka dark alex
+DNSSEC-Implementation by Alexander Täffner aka dark alex
 */
 
 class cronjob_bind_dnssec extends cronjob {
@@ -59,6 +59,9 @@ private function increase_serial($serial){
 
 	public function onRunJob() {
 		global $app, $conf;
+		
+		//* job should only run on ispc master
+		if($app->db->dbHost != $app->dbmaster->dbHost) return;
 
 		//* Load libraries
 		$app->uses("getconf,tpl");