Re-indexed disallowed array because of json_encode issue

Re-indexed disallowed array because of json_encode issue with non-sequential array

See example #3 here: http://www.php.net/manual/en/function.json-encode.php

If we are dealing with a non-sequential array json_encode transform it into an object, so CMSMain.Tree.js can't handle it, resulting in $allowed_children and $can_create (and maybe others) not honored in contextual menu.