v2.2.2 Pop

Changelog

#4093 Bump redcarpet from 3.4.0 to 3.5.0
#4091 Move CSS rule to SCSS and remove broken css file reference
#4089 Add doctype declaration in layouts/admin view
#4086 Transifex
#4075 [Defacepocalypse] De-deface payment methods index
#4067 Add icon to OC menu entry
#4066 Organizing spec/serializers - put each file in the correct place
#4065 Brings in the latest Spree fork's Git commit
#4061 Revert "Handle soft deleted variants in order edit"
#4059 Convert 2 rabl templates to AMS and remove a few unused ones
#4049 De-deface admin orders adjustments page and customer details page
#4047 De-deface some admin configuration pages and the general admin layout and menu
#4043 Bring spree/admin/orders/shipment and shipment_manifest partials from spree_backend and fix an authorization bug
#3938 Handle soft deleted variants in order edit
#3786 sticky header for mobile
#3700 Remove dependency to spree_auth_devise