fixes failing i18n specs

Eliminates registering_with_oauth attr_accessor

ELIMINATE

Conflicts:
	app/views/users/registrations/finish_signup.html.erb

improves devise confirmation message

improves devise omniauth confirmation message

improves devise omniauth confirmation message

do not use nils on finish_signup fields

Fixes auth specs after changing the i18n

app/models/user.rb

@@ -39,7 +39,6 @@ class User < ActiveRecord::Base
   accepts_nested_attributes_for :organization, update_only: true
 
   attr_accessor :skip_password_validation
-  attr_accessor :registering_with_oauth
 
   scope :administrators, -> { joins(:administrators) }
   scope :moderators,     -> { joins(:moderator) }