If there's demographic data for all participants, it doesn't make sense
to show the message.
We're using translations instead of an `if` in the view because the text
is also different when there's only one participant. In some languages
the text might also be different depending on how many people with no
demographic data participated.
Another possibility would be to use an `if` in the view so we don't
display an empty paragraph when the cont is zero, and then using
translation for `one` and `other`. I haven't gone that way because I
thought the logic would be more complex and the benefits wouldn't be
that great.
For now we think showing them would be showing too much data and it
would be a bit confusing.
I've been tempted to just remove the view and keep the methods in the
model in case they're used by other institutions using CONSUL. However,
it's probably better to wait until we're asked to re-implement them, and
in the meantime we don't maintain code nobody uses. The code wasn't that
great to start with (I know it because I wrote it).
So now stats by gender and age are replaced by shared participation
stats (which also includes stats by district), reusing the code already
used in poll stats, and advanced statistics (which used to be at the top
of the page) are now displayed after partipation stats.
