Basic support of Stripe Connect

[clawfire]

The idea here is to work on #542

So I added some elements in the blade StripeSCA config blade to be able to define:

• The transfer account (only support one at that time)
• The fee you want to add (fixed amount so far)

When computing the fee to pass to the transfer account, I sum the Booking fees and the fee defined before. Why? Because when you're doing a connect payment, the main account is supporting the Stripe fee, not the destination account. So I use the Booking fee to cover Stripe's fee and add the custom fixed amount fee.

That's indeed questionable. It works for me, it wouldn't work for everyone. Would be better, probably, to have all of this configured into the Stripe SCA blade under a Stripe Connect Section.

I would be glad to get your feedbacks.

[clawfire]

Thanks, @justynpride for the language, I didn't find them 😃
Added some extra security to test if stripe connect settings are set or not.

[clawfire]

Still blocked by #994 to be able to test properly 😃

[clawfire]

I'm really pissed because I realize Omnipay only support a destination for a charge but does not pass the application_fee parameters, even through a transactionFee they tell us to use in the documentation but which is present nowhere in their code base :/

I should then redirect my effort on just supporting the destination account without specifying fees.

My knowledge on Attendize is limited, but regarding omnipay, it could be achieved by doing the transaction in a regular way; THEN creating a transfer manually through the API.