Add an address import/export tool

[gthayer]

Request received here: https://wordpress.org/support/topic/is-it-possible-to-import-addresses-per-customer/

[Hinyka]

At the end of last year I created a fully functional concept. https://github.com/Hinyka/woo-address-book/commit/7886b93d8063136088d22894d572792d4a7a3c68 Which, allows to import/export user's own addresses.

Unfortunately, due to the constant lack of time, the code is not ready for stable deployment. @matt-h Maybe for a new branch?

Possible issues and todo:

• it will be better to add quotation marks when using a comma as a delimiter
• add success / failure verification
• add the option for the administrator to import/export addresses for multiple users at once

[matt-h]

Thanks @Hinyka This looks like a really good start and is most of the way there. Go ahead and make a Draft Pull Request with it and we can work to finish it off to get it ready.