Removes a lot of logic out of the controller and into model per https://github.com/spree/spree/pull/4331
Removes a lot of logic out of the controller and into model per https://github.com/spree/spree/pull/4331

spree-contrib/spree_multi_currency,sspinc/spree_multi_currency,dgross881/spree_multi_currency,Lostmyname/spree_multi_currency,spree-contrib/spree_multi_currency,raulpopadineti/spree_multi_currency,Lostmyname/spree_multi_currency,Lostmyname/spree_multi_currency,raulpopadineti/spree_multi_currency,spree-contrib/spree_multi_currency,dgross881/spree_multi_currency,sspinc/spree_multi_currency,raulpopadineti/spree_multi_currency,sspinc/spree_multi_currency,dgross881/spree_multi_currency