Backport Ukrainian translation from master
[uk] add missing strings & fix errors
[uk] add missing translations
[uk] продукт -> товар
[uk] add parameter to :order_number
[uk] fix badly translated term
[uk] devise.user -> devise.spree_user
[uk] translate spree.change_my_password
[uk] fix typos
[uk] fix typos and errors
[uk] Відміна -> Скасувати
Merge branch 'backport-uk-2-3' of https://github.com/hnatt/spree_i18n into 2-3-stable