fix nested select when used inside a nested form

Author: rubenbe

app/assets/javascripts/activeadmin_addons/inputs/nested-select.js

@@ -151,6 +151,9 @@ var initializer = function() {
 
       if (!!parent) {
         var parentSelectorId = '#' + model + '_' + parent;
+        if (!$(parentSelectorId).length) {
+          parentSelectorId = $(container).find('*[id*=' + parent + ']')[0];
+        }
         var parentSelector = $(parentSelectorId)[0];
 
         $(parentSelector).on('select2:select', setParentValue);