WorldPay: Use the Sale API

Instead of two API calls (authorize and deposit) we should
use the 'Sale' API call which does them both in the same step.

Advantage here is that this API also supports recurring payments
with some optional keys that I didn't add.

Change-Id: Ida9f5b141742d78ec6a8f7871d6f35f361ae427a
Merge "WorldPay: Use the Sale API"