Worldwide shipping

[jjeffryes]

Edit Item:

• when editing a physical item, Worldwide shipping is the default option
• when selecting shipping regions, if a non-worldwide value is selected, worldwide is removed. If worldwide is selected, all other values are removed
• buttons for the EU and the EEA can be pressed to auto-select those countries
• if the product is digital or a service, NA is saved as the ships_to value
• description fields can no longer have

  tags with no text when the Medium-Editor leaves empty paragraphs

• when a field is invalid, the error message now displays the translated label text, not the id
• the ships_to field is validated so it cannot be blank, and is highlighted with the standard invalid field style when it is
• the minimum price for shipping is now zero

Item:

• the country of origin is now the "pretty" country name from the countries model if available, or the country name from the user's settings if not (digital and service)
• the country name has a tooltip that shows the full country name if it is too long
• formatting on the data displayed next to the country name was cleaned up and the HTML was refactored to use flex boxes
• if the product can be shipped to one of the saved addresses of the user, the countries from those addresses are displayed.
• all the countries the product can be shipped to are displayed in the shipping tab
• the country of origin is displayed next to the domestic shipping price in the shipping tab

Transaction modal:

• if shipping is worldwide, all addresses are considered valid
• the purchase button and back button are disabled immediately after clicking the purchase button, instead of waiting for a reply from the server to prevent multiple server calls
• if a new purchase call is made, or the modal is closed, the current purchase call is aborted, to prevent error messages appearing after navigating away from the view
• once a purchase is complete, clicking the purchase page link in the modal will close the modal
• long addresses no longer break the layout

Closes #351
Closes #501
Closes #702
Closes #943 (I think, the issue is unclear)
Closes #982
Closes #1017
Closes #1024
Closes #1034