Use email regex from Devise. Fixes #5368
Implemented fix for duplicate addresses being created in checkout
Fixes #5370
Added failed state to the admin variables

A payment state could be `failed`.
This state was missing from the admin variables.
The payment state had no color, it was just a blank circle. I added the red color.
I noticed this in spree 2-2-stable.

Fixes #5378

Conflicts:
	backend/app/assets/stylesheets/spree/backend/globals/_variables.scss
Fix variable css.
add select2 call after loading new images
Fixes #5385