If users participated and were hidden after participating, we should
still count them in the participants stats.
In the tests, we set users' `hidden_at` attribute before they vote.
Although in real life they would vote first and then they would be
hidden, I've written the tests like this for the sake of simplicity.
It will make it far easier to call other methods on the stats object,
and we're already caching the methods.
We had to remove the view fragment caching because the stats object
isn't as easy to cache. The good thing about it is the view will
automatically be updated when we change logic regarding which stats to
show, and the methods taking long to execute are cached in the model.
We were expecting `balloters` to include `poll_ballot_voters` (that's
why we're substracting them to calculate web participants), but reality
has proven `poll_ballot_voters` aren't included in `balloters`.
This spec was leaving the DB "dirty" because it was creating
records in a before(:all) hook. These records are not cleaned up
automatically when using the :transaction strategy for DatabaseCleaner.
Using before(:each), however, causes another problem. Some of the code
depends on the heading id being 1 (see app/models/budget/ballot/line.rb#L48).
Because of SQL auto-increment, this is only the case the first time the hook
is run, as different id's are assigned on subsequent runs. This is fixed
by forcing the id to always be 1.
