Add position counts to organisation people page
Use a CBV for organisation detail page

This makes it easier to subclass in the country apps to override small
bits of functionality for that page.
Override organisation detail view in south_africa app

We're going to have different organisation views depending on what type
of organisation it is, this logic makes most sense in the SA app so it
doesn't affect other things.
Use a different method to override the url in SA

This is not an ideal solution, but seems to do the job. The problem with
the way it was previously was that it the /organisation/all route way
getting skipped as the /organisation/:slug route was always matching.
Don't match organisation twice in the url
Give the "house" organisations a separate template.
Make sure the extends tag is first in the template
Add organisation name and kind to house page
Expose a list of all parties to the house template
Output people and parties on house page
Handle a '+' in organisation slugs
Revert "Handle a '+' in organisation slugs"

This problem goes deeper than just a single slug.

This reverts commit 42d0edb5fcd71634dccf030cf3daa54e606de0f8.
Merge branch 'master' into people-list-extras
Link to people page from house page
Calculate percentages of parties representing a house
Update template to render party percentages
Tidy up organisation house template
Make it clearer what the org details view is doing
Merge branch 'people-list-extras'