Replace I18n.t for Spree.t
Require at least one category for shipping method

[Fixes #3011]
Display validation errors on payment method create

[Fixes #3010]
Display text input if country has no state on backend

[Fixes #2999]
Check if order state is payment to accept payments

Redirect to payments/new when order has no payment
Also remove Continue bottom from orders/payments page,

[Fixes #2996]
[Fixes #2995]
[Fixes #2997]
Skip Deleted Stock Items in Stock Management Screen
pretty time should use capital M for month; fixes #3018