Update Radicale to 3.1.8
Fix setuptools requirement if installing wheel
Tests: Switch from python setup.py test to tox
Small changes to build system configuration and tests
Fix random href fallback
The Radicale Project is a CalDAV (calendar) and CardDAV (contact) server solution.
Calendars and address books can be viewed, edited and synced by calendar and contact clients on mobile phones or computers.
Officially supported clients are listed here, other DAV compatible clients may work as well.