Added shipping to configuration

[ehsanen]

It enables the Shop owners to hide Shipping address in Paypal website, in case their product is virtual, digital, or do not require shipment for any reason. It causes less confusions for customers.

[angelleye]

I'll do a quick review and merge this into our 1.1.6.3.6 update. Thanks for your contribution!

[angelleye]

Ah, actually, you'll notice we've already been discussing this in other issues.

In #174 we've added a "no shipping required" check box next to the downloadable / virtual check boxes in WooCommerce item details.

In #175 it's mentioned that we should add a global like what you've done here, so we may very well still merge this in. What we did in that issue, though, was add toggles so that you can easily enable/disable the "no shipping required" option on multiple items at once.

While those adjustments have already been made in those issue branches, I have yet to review them. I still need to pull those changes so I can review everything, and we'll probably end up with a mixture of all of this.

I'm going to go ahead and move this to the 1.2 release, though, so I don't delay the 1.1.6.3.6 update which is almost done.