Fix a typo ('the the')
Add a 'Not standing again' button to candidates from 2010

Previously, for the candidates from 2010 that we don't know anything about
yet, there wasn't a button for "Not standing again", only one for
"Standing again". This fixes that, adding a "Not standing again" button
as well.

This fixes #5
Factor out repetitive template code on the constituency page
Add a person's latest constituency as a breadcrumb in the person view

Fixes #41
Add an action log, to record what people do on the site

The idea is to have some log of what particular users are doing that is
distinct from the versions element of each PopIt person.
Display the action log in the admin interface