Configure calling cards for Sky DANCE

Steps:

1. Build a calling card account using the billing system

a) Create a rate group https://astpp.readthedocs.io/en/v3.6/Modules/Tariff/create_rate_group.html
b) Create a customer https://astpp.readthedocs.io/en/v3.6/Modules/Accounts/create_account.html
c) Add the customer number into Sky DANCE