Add I18n Localization for Error Messages

This adds support for easy I18n error messages when failing a context inside your action.

```ruby
class FooAction
  include LightService::Action

  executed do |context|
    unless service_call.success?
      failure_reason = case service_call.error_code
      when 100 then :rate_limit_exceeded
      end

      context.fail!(failure_reason, nil, self)
    end
  end
end
```

This would expect to find a translation of `foo_action.light_service.failures.rate_limit_exceeded`.  This works with nested classes as well via ActiveSupport standard methods.