Post Code wildcard support and case insensitive

Thanks for the plugin!
WooCommerce works supporting postcode wildcards which is needed for countries like Canada and the UK where postcodes are V4L2B9 for example. Normally you’d want to capture this postcode with V4L* in WooCommerce.

Also the postcode needs be case insensitive, currently expects uppercase E.G: ‘v4l 2s0’ should match with ‘V4L*’