Revert "default: Invoke pam_gnome_keyring in auth step"

This causes problem when setting up goa accounts where we get an empty dialog prompt that can't be canceled since gcr gets confused.

Revert until we have a proper solution.

I hope to have a closer look at the problem soon but this unbreaks the images for the moment.

This reverts commit 2849cd6d.

Closes #55 (closed) Reopens OS-issues#65