Make org slug changer add CIP redirects

These live under the org's namespace, and therefore need redirects put
in place.
Add extra log output with redirect info.

In order to help with adding the redirects to router-data this now spits
out the necessary CSV lines at the end of the run.
Update case_study.json schema with new links
Add policies & world priorities to case study format
Republish all publicly visible case studies

This is to add related policies and worldwide priorities to their links hashes.
Remove indirection
Merge pull request #1892 from alphagov/meta-data-for-case-study-format

Meta data for case study format
Render archiving explanations as govspeak.
Merge pull request #1895 from alphagov/govspeak-in-archiving-explanations

Render archiving explanations as govspeak.
Fix redirects on existing Unpublishings.
Tweak data migration logging output
Parameterise whitehall public root

This ensures the data migration does the right thing, regardless of the
environment it is run in.
Repair alternative urls with stray whitespace

At least 4 Unpublishings have alternative urls with a stray whitespace at the
beginning. This will remove any stray whitespace.
Merge pull request #1894 from alphagov/fix-unpublishings

Fix redirects on existing Unpublishings.
Remove left-over CIP tables

we migrated CIP model to be an Edition instead
of being a stand-alone model a while ago:

https://github.com/alphagov/whitehall/pull/1422

this cleans up the tables left behind.
Merge pull request #1881 from alphagov/org_slug_changer_cip_handling

Make organisation slug changer add CIP redirects
Check for markup equivalence, not string match

This gets around the issue of different versions of libxml generating subtly
different whitespace/newline output.
Merge pull request #1899 from alphagov/make-tests-more-robust

Check for markup equivalence, not string match
Add more links to services and information pages

This commit turns on the link for the HMRC services and information
page: this is a time-critical change which needs to go out on Wednesday
10th December - and HMRC will need to be informed so that they can
remove a duplicate link from their organisation page when it has been
deployed.

It also adds links for several other organisations (DfE, HS2, DVSA);
these ones are not time-critical.
More unpublishing repairs

This converts a bunch of auto-redirecting unpublishings so that they do not
automatically redirect as they are not on GOV.UK. Instead, a splash page will be
shown. This is because the Publishing 2.0 stack does not support non-GOVUK
redirects at present, and whitehall Unpublishings are not valid without a GOVUK
alternative URL.