Only serve statistics publications from /statistics

They were still routable from /publications, as well as /statistics, which is bad.
Serve them from one authorative place, and support any use of old style with redirects

Removes a couple of old tests for statistics-behaviour on publication views. The first
of which failed when addin the redirect, the 2nd 2 silently pass, as they're refuting
a selector against an empty body.
Change stats announcement date change rules

A change note should only be provided if changing an already "confirmed"
release date. Otherwise, we ignore the change note.
Only show "change note" text area when required

If the current release date isn't confirmed, then the user won't need
to provide a change note.
Simplify logic on date changes

The logic was way more complicated than it needed to be; if the change
is to a confirmed date, then the change note is required. There is no
need to check exactly what sort of change it is.
Extract logic to before_filter for clarity

Statistics are now served under their own routing (i.e. under
/government/statistics/), so we should redirect any requests at
/government/publications/ there when the publication is a statistics
document.
Data migration to cleanup search index

This will remove the search index entries for the old-style publication
paths and re-index them with their new path.
Reinstate test coverage on national stats badge
Be more explicit about where the redirect is going

This makes it clearer that the redirect is sending the request to to a
different controller
Remove international development fund categories

International development funds are moving from whitehall to
specialist-publisher/specialist-frontend. Therefore we want to remove
them from collections browse and redirect the categories to the new
international development fund finder.
Merge pull request #1695 from alphagov/stats-change-note-tweak

Change stats announcement date change rules
Nullify the correct mainstream category field

Sometimes the category we're removing isn't the primary category but one
of the other categories. Handle that case.
Merge pull request #1672 from alphagov/duplicate-statistics-urls

Only serve statistics publications from /statistics
Redirect to filtered search results after publish

www.agileplannerapp.com/boards/173808/cards/5164

Currently when an editor publishes an edition,
we redirect them back to the editions results
with the filter reset to all published editions.

Following research, editors preferred to go back
to the filtered search results they were last at.
If they had not chosen search filters, we should
redirect them to their organisations published
editions.
Update dashboard link destinations

* Include ‘www’ in support link
* Switch development backlog from pivotal to agile planner
Merge pull request #1700 from alphagov/fix-whitehall-dashboard-links

Update dashboard link destinations
Tidy up table of organisations

* Pluralise headings
* Move create organisation action beneath heading
* Make table more legible using borders and table heading styles
* Remove empty nav container
Tidy up heading and table styles for big lists

* Move create actions beneath heading (and warning when there is one)
* Make table more legible using borders and table heading styles —
clearer divide between columns, clearer headers, clearer table
boundaries
* Remove empty nav container
Notify the router API to add redirects
Sort topic groups by their parents.
Whitespace.