Simply store the cookies to user data dir

[jaraco]

• Set the cookie on the response, more accurately modeling the real flow. Fails due to Cookies not propagated to requests.Session jamielennox/requests-mock#17.
• Rely on pre-release requests-mock as workaround for Cookies not propagated to requests.Session jamielennox/requests-mock#17.
• Set the UUID at login and load it from cookies.
• Replace manual cache with shelf-backed cookie jar.
• Declare dependency on jaraco.net 8
• Move requests_mock workaround to tox config as it will block a release.
• Explicitly close the cookies so they can be opened by another client.
• Rely on jaraco.net 9 for json-based cookie shelves.