This will make it easier to mock the calls in our new stripe mocking
framework. I believe the two forms are equivalent, assuming the Stripe
Python bindings aren't doing anything crazy. And if not, well hopefully our
new testing framework will catch it :).
[Idea originally from Vishnu KS.]
This will improve both the maintainability and accuracy of the fixture
data. It also makes it less scary to upgrade Stripe API versions.
[With significant changes by Rishi Gupta.]
There are several situations in which we want to create a Customer and
stripe.Customer object before we really have a billing relationship with a
customer. The main one is giving non-profit or educational discounts.
The main purpose of this commit is to demonstrate end-to-end that
our setup for type stubs works. I picked this library more or less
arbitrarily as one where the API surface we use is tiny, so that the
stub would be extra easy to write.
