v1.4.0

• Add a requirement for devise 3.1 and above.
• Removed backwards compatibility for mailer tokens for devise versions before 3.1.0. Any views generated into your app prior to this release of devise-i18n should continue to work. If, for some reason, you are otherwise calling DeviseI18n::ViewHelpers methods (resource_confirmation_token, resource_reset_password_token, and resource_unlock_token), you will need to replace these calls with @token.
• Update ja translation.