add Upload field

* Fix warning messages "implode(): Invalid arguments passed..."

* Fixed: register_taxonomies and register_post_types was hooking the …

…after_setup_theme instead of init.

* Fixed: created default POST params to avoid "Undefined index" notices.
* Fixed: testing if field exists before trying to access it.
* Fixed: testing hide_type field before accessing it.
* Fixed: handling not found custom field to avoid output of Array.

= 1.3.5.6 - 2014-07-06 Arnold Bailey

* Added "required" attribute override to the [ct_in] shortcode.
* Fixed network level taxonomy edit which was losing field settings.
* Allow ascending and descending sort of custom field options in
dropdowns radio checkbox lists.
* Fixed radio button custom fields not setting to their default.