modal.js: Submit form only once

public/js/icinga/behavior/modal.js

@@ -90,6 +90,8 @@
         var _this = event.data.self;
         var $form = $(event.currentTarget).closest('form');
         var $modal = $form.closest('#modal');
+        // otherwise the form is submitted several times by clicking the "Submit" button several times
+        $form.find('input:not(:disabled)').prop('disabled', true);
 
         var req = _this.icinga.loader.submitForm($form, $autoSubmittedBy);
         req.addToHistory = false;