Note that this is one of the few fixtures that isn't tested against
a running server. But it still makes sense to move it to fixtures.json so
that it is rendered with indenting and a space after every `:` by
the api_code_example extension.
We now have a separate page for common error payloads, for example,
the payload for when the client's API key is invalid. All error
payloads that are presented on this page will be tested similarly
to our other non-error sample fixtures.
It makes sense to make our Python and JS API examples more visible
than our curl examples, since Python is what most people will tend
to use.
Also, from a design perspective, an API documentation page that
starts off with a shiny Python example with syntax highlighting
looked much better than having a bland curl example be the first
thing readers see.