Redirect /specialist-documents to /cma-cases

Permanently redirect old urls to specialist-documents to /cma-case
Merge pull request #150 from alphagov/redirect-specialist-documents-to-cma-cases

Redirect /specialist-documents to /cma-cases
Publishing script republishes CMA cases correctly.

To prepare for republishing multiple types of document (other than just
specialist documents) we needed to fix the republishing script to both
operate without errors and to correctly notify the right set of
observers.

The eventual aim is to provide a two-level array of repositories and
the listeners that should be notified which will then perform
republishing for all types of documents.
Removed more unecessary code related to SpecialistDocument#published_version

Rename exposed_edition back to latest_edition
Merge pull request #151 from alphagov/republishing_script_fixes

Publishing script republishes CMA cases correctly.
Create migration to turn dates into strings.

This migration will turn the opened_date and closed_date on all
cma_cases, including both the bare attributes and extra_fields.

There's a big comment in the code about some weirdness with mongoid,
too.

Thanks mongoid. Thongoid.
Merge pull request #154 from alphagov/normalize_dates_for_specialist_documents

Create migration to turn dates into strings.
Index CMA cases in Rummager on publish

Also remove them from Rummager when they're withdrawn.
Remove dependency on SpecialistDocumentAttachmentProcessor
Add spec for CmaCaseIndexableFormatter
Stub Rummager requests in cukes
Assert Rummager API is called in cukes

Define a `rummager_api` in the wiring so that we can use RSpec to spy on
the method calls it receives.
Merge pull request #148 from alphagov/rummager-integration

Index CMA cases in Rummager
Bump govuk_content_models to v13.4.0
Give Document formatters specific "kind"

Instead of being generic about how we register documents with panopticon give them an explicit "kind" which is stored with the PanopticonMapping as resource_type. In order to find these again we will need to change the PanopticonMapping#documents scope to pull all types of specialist-document.

While we are here lets also rename DocumentArtefactFormatter to a CmaCaseArtefactFormatter which is its correct name!