Efficient tests clean up with Organisation API

[AuHau]

From talking with Toggl's support, it should be possible to make more efficient integration tests cleanup with using Organisation API, where we would delete the whole organization and recreate it before running the tests. This would make the cleanup more or less two API calls compared to calling DELETE on every entity that we do now.

But that will require to add more support for Organisation API, or call those endpoints manually. I am for now parking this as it seems that current integration tests setup works again, but if somebody would be interested feel free to jump in!