It would take ages to go through all files now and assess all belongs_to
associations. So I just declare the old default and then we can move on
and apply the new default for the application while these classes still
use the old one. All new models will then use the new default which is
the goal of this excercise and we can refactor old classes when we touch
them anyway.
#update_column(s) skips callbacks (which is useful), but it doesn't change the updated_at field on the record by default (which we should be doing in these cases).
This change is made in Spree 2.2 here: b367c629ce
