Add IBAN field to supplier and user model

app/views/admin/configs/_tab_payment.html.haml

@@ -10,6 +10,7 @@
   .input-prepend
     %span.add-on= t 'number.currency.format.unit'
     = config_input_field form, :minimum_balance, as: :decimal, class: 'input-small'
+= config_input form, :use_iban, as: :boolean
 
 %h4= t '.schedule_title'
 = form.simple_fields_for :order_schedule do |fields|