add payment_amount_human_readable for the admin list not just the sin…

…gle view (#643)

app/controllers/registration_controller.rb

@@ -316,6 +316,7 @@ def get_registrations(competition_id, only_attending: false)
             },
             payment: {
               payment_status: x.payment_status,
+              payment_amount_human_readable: x.payment_amount_human_readable,
               updated_at: x.payment_date,
             },
             guests: x.guests }