DeleteDowntimesCommandForm: Allow iterable for setDowntimes()

The command form loops over the downtimes to delete. It is not necessary
to expect an array here. The Icinga DB web module passes an iterable
here.

modules/monitoring/application/forms/Command/Object/DeleteDowntimesCommandForm.php

@@ -30,11 +30,11 @@ class DeleteDowntimesCommandForm extends CommandForm
     /**
      * Set the downtimes to delete
      *
-     * @param   array $downtimes
+     * @param   iterable $downtimes
      *
      * @return  $this
      */
-    public function setDowntimes(array $downtimes)
+    public function setDowntimes($downtimes)
     {
         $this->downtimes = $downtimes;
         return $this;