Optimization on the queryset

Rather than load all the td/cp/bar for each county and then look at the
length of the list, (which is a "SELECT * FROM..") instead do a queryset
exists which does a "SELECT COUN(*)". Speeds up the query.
Optimization of queryset.

prefetch_related will load all the objects straight away, even if we
don't need them (it's eager loading, not lazy loading)

However with the previous change to use .count on the queryset, then we
don't need eager loading. This massively reduces the querys
Optimize the queryset. Make use of SQL indexes

In MySQL, the old query was doing "SELECT * FROM.. ORDER BY name" which reads the
whole table. Now it's doing "SELECT id, name, url_path FROM... ORDER BY
name", which means it can now use the 'name' index, making this query
x10 times faster IME.
release v1.0.0