[Zurich] fix moderated statistics to include hidden

As per comments after testing mysociety/FixMyStreet-Commercial#459, the
business logic of the actual state changes is fine, but the stats do
also then need to include hidden records.
[Zurich] also allow hidden reports for closed_overdue
[Zurich] testing - create superuser earlier

So that tests pass on clean dataset such as travis...
Merge branch 'zurich-problem-status-stats'