For some reason running `bundle exec rake db:migrate RAILS_ENV=staging`
fails with:
```
rake aborted!
NameError: uninitialized constant Spree::Config
```
Running `bundle exec rails server` for instance, does not. There must be
a difference on the way a rake task and the rails commands load the app.
Moving this configuration to an initializer, at the end of the
initialization process, fixes it. The constant `Spree::Config` is
already loaded.
**This is preventing the release v1.22.0 from being staged and tested**