Fetch active variant only in order import through api

Fixes #3647
standardized address attributes in api_helpers

Fixes #3646
adds awesome nested sets's 'depth' field in taxons

Fixes #3634
Cleanup Zone Editing

Fixes #3631
Remove promo related deprecated code

Fixes #3563
Order shipping rates by cost ascending

This fixes a problem on the frontend that I saw where they were displaying in indeterminate ordering
Add HUGE GIANT WARNING to installation section of README

Related to #3653
Address information is now only accessible through an order

This is because we need to first look up if the user has permission to view the order. If the user has the additional permission of being able to modify the order, then they should be able to modify the address too.

Fixes #3635