WooCommerce Advanced Product Labels 1.3.1

* fix - Autoload updated (fixes incidental issue with old updater initiated from another plugin)
* fix - Responsive fix in backend
* fix - Error when creating a new label, without configuring it
* fix - Custom CSS live update
* fix - Save button not activated on Advanced setting change (Woo 9.3+)
* add - Show variables with the label configuration
* add - {stock} variable, converts to quantity in stock for the product
* add - {sales} variable, converts to total sales for the product
* update - Clean formatting/styling on the back-end.

* [Improvement] - Clear object cache when saving a global label to ensure changes come through with persistent cache
* [Improvement] - Product age condition improvements
* [Fix] - Missing textdomains

* [Add] - Declare HPOS compatibility
* [Update] - Bump minimum PHP version to 7.0
* [Improvement] - Update WP Conditions to 1.0.13
* [Fix] - 'Bestseller' condition not always working as expected
* [Remove] - Removed the deprecated WAPL_Label class