Add disabled field on User

www.agileplannerapp.com/boards/173808/cards/5886

This helps filters out users based on their Signon
state. For example, Signon would inform this app
about a user being suspended by setting `disabled`
in the user json.
Remove international delegations from embassy finder
Filter-out disabled users from lists and selects

www.agileplannerapp.com/boards/173808/cards/5886

Disabled users for now are suspended users in Signon.
They get synced over by [GDS::SSO](https://github.com/alphagov/gds-sso/pull/62).
Merge pull request #1856 from alphagov/remove-international-delegations-from-embassy-finder

Remove international delegations from embassy finder
Add a data migration to redirect phillip-marsden to philip-marsden

- Someone added a ticket to the second-line backlog to rename this
  person's slug due to a typo when it was first created. After a chat
  with Tekin, this was deemed the easiest way. This fixes, in this
  case, the bad spelling of Philip.
Merge pull request #1855 from alphagov/ignore-disabled-users

Filter-out disabled users where users are listed
Merge pull request #1861 from alphagov/rename_person_philip_marsden_slug

Add a data migration to redirect phillip-marsden to philip-marsden
Correct data migrations

These data migrations have been run now, but I'm correcting them here to be safe
in case folk use them as a reference in future.
Add CSV permission for all departmental editors

Allow all departmental editors to export the document list as a CSV.
Merge pull request #1863 from alphagov/correct-data-migration

Correct data migrations
Add an admin API for reindexing sector editions.

In order to get tag information for published
editions into Rummager (and thence to the services
and information page, among others) when a draft
specialist sector is published, we need to notify
Whitehall so it can resubmit all published editions
tagged with that specialist sector.
Merge pull request #1865 from alphagov/add-topic-reindex-endpoint

Add an admin API for reindexing sector editions.

https://www.pivotaltracker.com/story/show/83216078
Refactor building of Publishing API presenters

Moves the knowledge for presenting a given model into one place.
Replace bespoke workers with a generic one

Now we have a way to instantiate the correct presenter for a given model
instance, we can use a generic Publishing API worker to push any model we like
to the Publishing API, assuming a presenter exists.

Note that the existing workers have not been removed yet. They can be removed in
a later pull request once any existing queued jobs have been worked off.
Data hygiene class for (re)publishing instances

Convenience class for pushing a bunch of models to the Publishing API. We're
likely to be doing this a lot whilst we're moving content to the content store
and evolving the data that we send.
Ensure class namespacing is honored
Don't misuse Struct

Turns out that subclassing Struct causes issues with Rails class reloading.
Besides which, it also appears to be a bit of an anti-pattern, as outlined here:
http://thepugautomatic.com/2013/08/struct-inheritance-is-overused/.
Merge pull request #1864 from alphagov/extend-export-csv-permission

Add CSV permission for all departmental editors
Add a data migration to rename a gambling duties document collection

- There was a ticket in the second-line backlog about renaming this
  document collection because it referenced "forms", which the page no
  longer housed. Now it only references "notices". It was decided that
  this data migration approach was the most sensible, following on from
  #1861.
- In this data migration, I've also added a line to remove the old
  collection from the search index, so the same titled document won't
  appear twice - thanks Tekin.
Fix data migration