Make two URLs for the two County Performance experiments

We don't want to risk people following links from the earlier trial
experiment while the larger experiment is running and the data being
contaminated by that. The safest way to do that is to use two different
base URLs for the two experiments - one is now /county-performance and
the other is /county-performance-2

The commit introduces that change, while reusing the same view classes
with minor modifications.
MIT: fix failing County Performance page tests

There is a better fix for this in the split-county-experiments branch,
which should be merged shortly.
Update za-hansard to the version that uses the new PopIt instance
Fix a circular import bug when running South Africa tests in isolation

When running South Africa tests in isolation, this would fail with:

    File "/home/mark/pombola/pombola/pombola/south_africa/urls.py", line 4, in <module>
      from pombola.south_africa import views
  ImportError: cannot import name views

This was caused by a circular import caused by importing
PersonSpeakerMappingsMixin from pombola.south_africa.views instead of
pombola.core.views (where it's actually defined in any case).
Update pombola_person_to_sayit_speaker for created-from-Pombola PopIts

We're now standardizing on doing name resolution in the South Africa
scrapers from PopIt instances that are mirrored from the Pombola
database. This means that we should now derive the PopIt ID from the
primary key in the Pombola database rather than one of the Identifier
objects.
Teach SASpeakerRedirectView that Person primary keys are in PopIt IDs
Use a new version of popit-resolver with improved name matching
Merge branch 'fix-name-resolution'
Update za-hansard to get a memory leak fix for the committee scraper
Merge branch 'split-county-experiments'

Conflicts:
	pombola/kenya/tests.py
MIT: update the social context text at Leah's request
Completely hide hidden people (don't even list them)

Previously we would still list people who were marked with hidden=True
and not link to their person page (which would 404 except for admins)
but this produced very unweildy lists of people on organisation or place
pages.

This commit changes this behaviour to not even list hidden people on
organisation or place pages.
KE: Add a script for hiding people on Mzalendo, as requested
MIT: correct a mispelling
MIT: set the Qualtrics survey ID for the new page
Add an API page, linking to PopIt and Popolo JSON exports

This depends on POPIT_API_URL being set in general.yml and nightly
mirroring to PopIt and dumps to Popolo JSON.

This is a partial fix for #1430 - the page would still need to be linked
to from elsewhere on the site as well (e.g. the nav bar and footer)
ZA: update installation instructions to refer to the generated Popolo JSON
Remove old Popolo JSON file

This is now provided by the API page