* Fix - Ensure estimated delivery dates aren't on weekends * Misc - Add support for WooCommerce 3.8
* Misc - Add support for WooCommerce 3.7 * Misc - Remove support for WooCommerce 2.6 * Misc - Require PHP 5.6+
* Fix - Ensure the chosen Shipwire shipping rate is passed on to exported order in WooCommerce 3.4+