Switching to using SayIt's master branch

This commit switches to using SayIt's master branch while still keeping
the namespaced structure of the URLs; this means there's some
redunancy in the URLs.
Remove redundancy in SayIt URLs, switch to a single namespace

Having the SayIt URLs split over three namespaces introduced a
redundant part of the URL when having switched to master, where
section slugs included the hierarchy of sections, e.g.:

  /hansard/hansard/2013/april/23/proceedings-of-the-national-assembly-tuesday-23-ap/notices-of-motion

To fix this, this commit switches to only using a single namespace,
where any path that doesn't match any other pattern in the URLconf
is matched as a section slug for SayIt.
Update the expected gecoder results
Use a local variable speech instead of self.object for clarity
Require a particular commit of SayIt, not master

As Matthew Somerville pointed out:

   "Just to note that I don't think the requirement commit should be
    moved back to master; this will immediately break any newly deployed
    Pombola as soon as an incompatible change is made in SayIt (e.g. all
    the redesign changes just merged today). I think the branch name
    should be maintained in SayIt and it can then choose to point at
    which ever commit will maintain working status."

I'm not sure it's worth still keeping the "pombola" branch in the
SayIt repository, though, since that might still cause surprise if
someone updates that branch without thinking about the consequences
for the next deploy - if we just require a particular commit, changes
to the version should (!) always be more thoughtful.
Switch SACommitteeIndexViewTest to use WebTest
Update SayIt to a version with the create_sections updates
Factor out the section title in SACommitteeIndexViewTest
Make django-sluggable uses a slugify function that downcases

The django-sluggable settings file by default just replaces spaces with
dashes rather than downcasing as well:

  https://github.com/mysociety/django-sluggable/blob/master/sluggable/settings.py

... so set it to use the default Django slugify function.
Redirect to source URL for committee minutes with public set to False

The default get_queryset for SpeechView will only return Speech
objects where public is True.  This creates problems for South
Africa, since we want to be able to follow results from a private
committee minutes through to the original URL.  So, this commit
overrides get_queryset, adds the redirection behaviour and tests
for that.

Fixes #1302.
Optionally let the ZA _breadcrumbs partial include the section itself

When used from a section view, it doesn't make sense to include the
section itself in the breadcrumbs.  However, from a speech view, we
might want to use this partial passing the section the speech is in,
in which case you would want that section to be rendered.  This adds
an includethis option so that you can get this behaviour.
Include the parent section breadcrumb on individual speech pages

This is one of the fixes requested in issue #1303.
Restyle the SayIt-based presentation of speeches in Pombola ZA

After switching to SayIt master, the presentation of the speeches
needed some work.  (In some ways it was accidentally improved, e.g.
in that the aspect ratio of thumbnail images of politicians was no
longer broken, but there was still plenty of room for improvement.

This adds some of Martin Wright's CSS work in the main SayIt
respository for style the section pages, and adds a simplified
version of the individual speech pages.

Overall, I think this is an improvement, but there's still plenty
of scope for improvement.