[15h February 2019] - Test period optimizations and related API / automation updates

Summary of changes:

• No transaction is created for the first free payment of test period transaction and custom charge date transaction.
• Before payment, test period transaction and custom charge date transaction will be shown only on the payment session page (Zahlungsübersicht / Payment Status) and the access page 
• Webhooks "transfer.successful" is not sent, but we are sending "subscription_state_changed"
• Zapier's "new payment" and "new product payment" will not be triggered for test period transaction and custom charge date transaction. Instead, a new zap "payment session updates" is available to replace it. 

Affected environments and cases: 

1. Invoices: No invoice is created on the first transaction of test period transaction and custom charge date transactions. The invoice will be created as soon as a first successful payment is processed.

2. Transaction list and customer lists: The transaction with test period will not be shown in the transaction list (https://elopage.com/cabinet/transfers) and customers will not be displayed into the customer list (https://elopage.com/common/customers) any longer. 

>> Instead, it will be displayed in the access list (https://staging.elopage.com/common/course_sessions) if the product bought is a course, and payment status list (https://staging.elopage.com/common/payment_sessions). 

3. Concerning the CSV file in payment status page, it is now giving the same info as the CSV on the transfers page (including info about payments, sellers, test period, additional fields etc). This is also valid in case you are using custom fields and need to export them. 

4. Webhooks: The action transfer.successful will only be sent once the first payment is made, but all other triggers function perfectly. 

In case of test period or custom charge date transaction, the action sent is: "subscription_state_changed"

Here's an example log of all parameters we will be forwarding: {"payment_session_id":19490,"payment_session_token":"mDKppJVheZcySC2JyWHZ","action":"subscription_state_changed","payer":{"email":"test@webhookpayment.com","first_name":"Virginie","last_name":"Hache","country":"Germany","city":"Berlin","street":"test ","zip":"12333","company":null,"vat_no":null,"phone":null},"product_id":1918,"payment_state":"active_subscription","recurring_form":"split","with_test_period":true,"with_custom_start":false,"event":"payment_session.installment.paying"}

5. Zapier: The zap new payment and new product payment will not be triggered with test period and custom charge date. Instead, the new zap "new payment session state change" will be triggered. 
It contains 2 new parameters: "with custom date = True/false" and "with test period = True/false) that provide more information.