We barely use this trait. In the votation type spec we're probably using
it wrong, and in the answer spec we assume one of the answers is going
to be "Yes".
The name `yes_no` is more expressive, since it makes it clear what the
answers are.
When accessing the URL `/admin/stats/budget_balloting?budget_id=X'
for a budget in a phase prior to the balloting phase, the following
error was raised due to the stats where not calculated yet.
Instead, we'll now show a flash message.
NoMethodError:
undefined method `[]' for nil:NilClass
./app/controllers/admin/stats_controller.rb:82
The `type: :feature` is automatically detected by RSpec because these
tests are inside the `spec/features` folder. Using `feature` re-adds a
`type: :feature` to these files, which will result in a conflict when we
upgrade to Rails 5.1's system tests.
Because of this change, we also need to change `background` to `before`
or else these tests will fail.
