Apparently, we didn't have one of these, and thus had a moderate
number of generally very old violations in the codebase. Fix this and
clear the ones that exist..
The fixture changes are because self.upgrade formerly used to cause a page load
of /billing, which in turn calls Customer.retrieve.
If we ran the full test suite with GENERATE_STRIPE_FIXTURES=True, we would
likely see several more Customer.retrieve.N.json's being deleted. But
keeping them there for now to keep the diff small.
This will change the hash of the URL when a new tab
gets selected. Vice versa when the billing page is opened
the appropriate tab is selected according to hash of
the URL. This means when the card gets updated the
page would be reloaded correctly to show #payment-method
tab.