Update PayPal API live URL

Starting some time on October 20th, PayPal's legacy API endpoint started to experience SSL connection errors. Presumably, they updated some configuration to avoid POODLE attacks and made a mistake in the configuration of the old endpoint. Switching to the new endpoint, fixes the connection issue. https://developer.paypal.com/webapps/developer/docs/classic/api/endpoints/ None of the other endpoints experienced the same issue.