bugfix unlimited backup files fails

v2/models/BackupSchedule.php

@@ -209,7 +209,9 @@ class BackupSchedule extends AbstractObject
             "starttime" => $this->getStarttime(),
         );
         if($this->getMaxfiles()){
-            $data['maxfiles'] = (int) $this->getMaxfiles();
+            if((int) $this->getMaxfiles() > 0){
+                $data['maxfiles'] = (int) $this->getMaxfiles();
+            }
         }
 
         if ($this->getStorage())