EL-207 Ability to disable an election
Use MySQL auto increment on some more tables to stop errors in the admin interface

Also need a migration: https://gist.github.com/4591345
This can return 0 when there are no links to delete
DRY title
Display postcode to electorate name mappings
Switch australian_postcodes to InnoDB so we can use transactions

Migration: https://gist.github.com/4591501
Bulk replace postcode mappings