Added Person#without_a_current_ministerial_role

This replaces and clarifies the intention of Person#non_current_ministerial_roles, and provides a test.
Change Searchable to respect :only param in update_in_search_index

Previously searchable_options[:only] was only used to scope the objects retrieved when using Class.search_index to index all the instances.  This meant if we only wanted to index some instances we had to deal with it in our own callbacks for normal lifecycle events.  Now the only param is used as a guard (by adding .find_by_id(self.id).present?) inside update_in_search_index so that if the instance is not present in the scope it won't be added to the search index.
Corporate info pages belonging to non-live orgs are not search indexed
Data migration to remove corp info pages and people wrongly indexed
More intelligent check that i18n files are up to date

Checking the file timestamp is no use because on CI the file timestamps
reflect the date when the files were checked out. There can be random 1
second differences so that this test would fail intermittently.

Now we check heirarchically that all keys present in the english locale
file are present in all other files.

We skip the language_names key because we don't translate every language
name into every locale.

Murray pointed out that some languages might not have the 'one' plural
form, so this test would always fail for such languages but we don't
currently have any such language, so I think it's ok.
Revert "Defer GC and scrub ivars to speed up test suite"

This seems to be causing issues on CI - worth reverting this just in case.

This reverts commit 3fda09c7d6c713c721b05bf0ccea95f5fea973f9.
Merge pull request #337 from alphagov/only-index-corp-info-pages-belonging-to-live-orgs

Only index corp info pages belonging to live orgs

https://www.pivotaltracker.com/story/show/45957935
Remove 'attachments' from html version slug
Merge pull request #338 from alphagov/remove-attachment-from-html-version-slug

Remove 'attachments' from html version slug

https://www.pivotaltracker.com/story/show/46065291
fixing warning css from bleeding ovder to excessive character count

https://www.pivotaltracker.com/story/show/46095741
GEO should have DCMS colour

https://www.pivotaltracker.com/story/show/46014817
Ensure navigation doesn't cover footer bar

The navigation was covering the brand bar on top of the footer when it
stopped. Extra padding on the bottom fixes that.

https://govuk.zendesk.com/tickets/71505
Reword step definitions to be more specific

So we can use the same for for worldwide priorities
Allow documents to be associated with priorities
Merge commit 'e9b50853d6b1870a3d5753b503beb80eaf2013d8' into documents-worldwide-priority
clean up merge