Delink addresses after an order is complete.

This is the bulk of the work for satisifying https://trello.com/c/7GAFlQEB. Commit message contains the full details. There is one other minor issue. On nibley this gem is before `spree_digital`. `spree_digital` clears out the entire state machine removing the transition hook installed in this commit making this commit ineffective.

Once this commit is merged that will allow me to bump the version of the Gemfile. While doing that I will change the order on the Gemfile so this gem is loaded after `spree_digital`.