Fix frontend statistics announcement bug

The most recent change note should always be displayed regardless of whether it
was the most recent change or not.
Remove unnecessary indirection

The use of a separate presenter here on the statistics_announcements#show action
is unnecessary indirection as pretty much all the methods required in the view
are already present on the model. It also makes it more likely that bugs like
the one fixed by the previous commit will occur.
Enable Estonian translations
Import Estonian translations
Remove exempt orgs thumbnails

• Remove unnecessary code from not_live page
• Remove nested css for that section on for exempt orgs
• Update styles for adjacent elements to fix layout
• Remove unsed code from helper
• Remove rake task for generating thumbnails

https://www.agileplannerapp.com/boards/105200/cards/5218
Removed unused screenshots
Change ISCO org screenshot

ISC currently don't have an accurate screenshot (it's of the Security
Services website) which potentially compromises their image as
impartial. They have supplied a new screenshot image in
https://govuk.zendesk.com/agent/tickets/856092 and this updates the
image to the one they supplied (scaled/cropped to 287x215 as per the
other images in this folder)
Merge pull request #1822 from alphagov/change-isc-screenshot

Change ISCO org screenshot
Revert "Change ISCO org screenshot"
Merge pull request #1823 from alphagov/revert-1822-change-isc-screenshot

Revert "Change ISCO org screenshot"
Merge pull request #1820 from alphagov/remove-external-org-thunmbnail

PO accepted according to @russelthorn
Merge pull request #1818 from alphagov/estonian-translations

Enable Estonian translations
Merge pull request #1815 from alphagov/fix-frontend-statistics-announcements-bug

Fix frontend statistics announcements bug
Migration to drop email curation queue table

www.agileplannerapp.com/boards/173808/cards/6034

we're removing the email curation queue feature
hence this table is no longer necessary.
Merge pull request #1824 from alphagov/remove-email-curation-queue-table

Migration to drop email curation queue table
Deleting document deletes collection memberships

www.agileplannerapp.com/boards/173808/cards/8071

a document collection cannot be re-editioned if its
groups contain deleted documents. if we destroy all
document collection group memberships when a document
is destroyed, this issue will not occur, and will
also make sure references to documents are valid.

also includes a data migration to delete ~230 dangling
`DocumentCollectionGroupMembership` records referring
to deleted documents, which were created in absence
of `dependent: delete_all`.
Merge pull request #1825 from alphagov/carry-forward-collection-documents-to-new-editions

Deleting document deletes collection memberships
Silently handle GovspeakContent that has gone

If an HtmlAttachment is deleted before the job is processed, the job will fail
and keep getting retried. Better to silently handle this situation.
Merge pull request #1829 from alphagov/handle-gone-govspeak-content

Silently handle GovspeakContent that has gone