Use I18n strings if available

[seccomiro]

Tries to call I18n.t!("email_address.#{name}") at error_message(). This could raise exceptions in two cases:

• I18n doesn't exist (because you are not on Rails)
• The key was not found on i18n YAML files for the current locale Both cases are caught by the rescue clause, which returns a string based on existing @errors. Now it's possible to define translations inside your Rails app in the regular way.