Replaced `ClientsVocabulary` with the `OrgUnitsVocabulary`.
Task: Reworked single-orgunit behavior in task forms.

The `responsible_client` field should only be available if there
are mor than one orgUnits. The earlier implementation has checked
the number of clients.
Delete clientid viewlet.

It has been replaced by org unit selector viewlet.
Move dossier label creation to dossier.
Drop unused public url functions.
Add meta-builder for test-fixtures.
Remove unused parameters.
Use admin-units for latex listing.
Use ogds_service for tasktemplates instead of get_current_client.