Skip subscribe on test

[kuboon]

https://github.com/fractaledmind/solid_errors/blob/b75251b35c28e53f4339cc01f2ed519367c7a6f0/lib/solid_errors/engine.rb#L15-L17

This line works on every RAILS_ENV.

I wrote ugly workaround on my config/environments/test.rb

config.after_initialize do
    Rails.error.unsubscribe(SolidErrors::Subscriber)
end

Which solution would be better?

1. Hard cord: Rails.error.subscribe(SolidErrors::Subscriber.new) unless Rails.env.test?
2. Supply config.rails_error_subscriber (default to true?)
3. Supply config.rails_error_subscribe_envs (default to ["production"]?)
4. Add unsubscribe document on README