WooCommerce Google Analytics Pro 2.2.0

* Fix - Update tracking snippet to always load analytics.js over HTTPS
* Fix - Ensure BACS and Cheque orders are being tracked

* Fix - Simplify order payment tracking and ensure COD orders are tracked
* Fix - Ensure refunds are properly tracked

* Fix - PHP notices if events are inactive
* Fix - Update remaining pre-WooCommerce 3.0 incompatibilities for order tracking