make explicit deposit in invoices work

app/views/admin/ordergroups/_form.html.haml

@@ -2,6 +2,7 @@
   %p= t('.first_paragraph', url: link_to(t('.here'), new_invite_path(id: @ordergroup.id), remote: true)).html_safe
 = simple_form_for [:admin, @ordergroup] do |f|
   - captured = capture do
+    = f.input :customer_number
     = f.input :contact_person
     = f.input :contact_phone
     = f.input :contact_address