Polylang for WooCommerce 2.1.4

* Requires WooCommerce 3.4 or higher, Polylang 2.7 or higher
* Don't allow users without manage_product_terms permissions to create categories using the product importer
* Add a WooCommerce step to the wizard
* Add compatibility with WooCommerce Free Gift Coupons
* Fix new account email sent in wrong language when the language is set from the content
* Fix variation name in "Pay for order" form

* Fix wrong subject & heading language for emails sent in bulk
* Fix wrong translation url when the shop is not translated
* WC Subscriptions: Fix translated variations not deleted when deleting a subscription variation.
* WC Composite Products: Fix fatal error when creating a new translation when the plugin WC Product Search is activated
* WC Composite Products: Fix PHP warnings

* Fix paged shop pages redirected to main shop page (introduced in 1.3.1)