I think it would be better to make `:cookie-spec-factory` a higher-level option, so a request would look like:

```clojure
(http/get "http://example.com" {:cookie-spec-factory my-factory})
```

So in that case, you'll need to pull out the param in the `request` function and either pass it into `add-client-params!`, or create a new function called `add-cookie-param` and move the cookie-specific stuff there.