Add a comment to explain why we only load some of our 3rd party modules.
Update the test path to work with K3.
Database::set_default_instance() is no longer necessary.
DB::update()->set() API changed.
Add purifier and image to the 3rd party module list.
DB::insert() API changed.
URL::current() went away - keep our version of it but make it work with the new K3 APIs.
Partway through getting the unit test controller working.