Override SearchView for SA

We need to group search results by model type, using a custom view this
should be possible by overriding `extra_context` on the view and
providing extra querysets for the discrete models we want results for.
Haystack views are not like Django views

It seems that the haystack views don't have an `as_view` method, so we
just treat it like a regular class instead.
Search for people and organisations separately in SA

As per the wireframes the results for people and organisations are
expected to be less, so we need to do separate queries for each of them
so we can still display them ordered by importance. Solution partly
inspired by this post on the django-haystack list [1]

> The only way to keep relevancy &
> group by model is either to run many queries (one per model - usually
> performant thanks to query caching) or to run the query and
> post-process the results, regrouping them as you go.

[1] https://groups.google.com/forum/#!msg/django-haystack/MWFU8mBKIMk/d4kAqYGGIvYJ
Override the South Africa search template

Because we're showing results in separate sections (see previous commit)
we need to take control of the html for it. This is a first pass at the
working html.