This reverts commit 2f7f6692.

As interaction is called early it can now miss the specialise setup, so it
have to be caught explicitly.

Thanks to this roles are updated in same transaction.

Validating computer may help the system to work.

Because is set later, it triggers consistency error before being set.

Plugin is already loaded in SlapOS product.

It should be replaced by SlapOSShadowAuthenticationPlugin.

It is nice to see error messages w/o swallowing exceptions while running
manually.

Goal of the configurator is to install those bt5.

Promise are not related to the configurator but to the 'core' functionnalities.

Only test fresh installation for now.