Add tellers to vote calculation in Rails

This was added to the PHP version in c3e9681175aa9a347caf2fcc687cfbe17d906775
Update the default parliament to be the current one
Fix up link generation
It should 404 if we can't find the division
Match what the PHP app does when you have a year without divisions

This also makes the Rails app handle non-existent parties like when
you pass a dodgy party name to the app.

It's pretty nasty but I claim I'm just matching the PHP app, which is
nasty.