Use the Carrierwave generated urls instead

Carrierwave already implements generating proper urls.
Reusing this allowes us to remove complex code.
It also has other benefits like default support for private storage on S3.

I have this branch currenlty working smoothly on production with private S3 storage
Fixes #151 #123

DirectUrl::direct_fog_url(with_path: true) can even be deprecated as it just calls url