WooCommerce 3.0 Integration

[allysonsouza]

Make the plugin ready to work with WooCommerce version 3.0.

TO DO Check in documentation what aspects needs to be modified to make the plugin works in WooCommerce 3.0 - 2.6.x to 3.0.0 Developer Migration Notes

• [x] Review the product type Registrations creation
• [x] Product type select not marked as registration
• [x] Change reports variations access data to use new CRUD