Add a test with typeorm to check that the example in the read me works

Hello community,

I'm currently working on a paypal integration in nest js and just found this repo.
Still actively maintained? Or should i look for something different?

Add a webhook type interface with subscription and transaction type interfaces

Add additional MD files in the wiki for how tos on how to create payments and subscriptions from start to finish. Including nonces etc. Reference these how to docs to the readme.

This will also include refunds, cancelations etc

Must also include all options in BraintreeTransactionInterface like how to add a customer, address etc. Maybe also validation?

So in reference to #19 After doing so it would probably be better off all methods were available instead of reimplementing them.

Add the create, find, cancel and update methods to BraintreeProvider class to manage subscriptions