Fix settings multi save

We were not undelegating our events on the element which was causing the
view to live on indefinitely in the background with its events still
bound.

core/admin/assets/js/views/settings.js

@@ -61,6 +61,7 @@
     Settings.Pane = Ghost.View.extend({
         destroy: function () {
             this.$el.removeClass('active');
+            this.undelegateEvents();
         },
 
         render: function () {