Filter stats announcements in admin by title/slug

www.agileplannerapp.com/boards/173808/cards/5170

this is just a first-pass at getting a search and
filter interface in place for stats announcements.
editors have an immediate need to start searching
by title and slug, so we put in place that first.
Move span9 container into parent template

* The JavaScript takes the HTML response and embeds it within the
container with a search_results ID. This leads to nested span9 elements
appearing within the page and duplicate elements with the same ID.
* This had the effect of showing a thinner results table when filtering
in-page.
Tidy up search result statistics

* Use number_with_delimiter for readable numbers
* Put the number and text into a left-to-right readable form, ie “3,956
documents” reads better than “Documents 3956”
Render importer error_list without layout on Ajax.

Prevents display of second page header etc.
jQuery .live has been removed, use .on
Merge pull request #1631 from alphagov/importer_errors_ajax_fix

Fix bugs with importer Ajax functions.
Merge pull request #1622 from alphagov/search-statistics-announcements

Filter stats announcements in admin by title/slug
Pluralise bulleted list and numbered list

Pluralise bulleted list and numbered list
Revert "Pluralise bulleted list and numbered list"

This reverts commit 96fb95077405b5a0756237e37f3e95ad98b4d4f1.
This commit was accidentally pushed to master. Helping-out
@marksheldonGDS to regularise his change.
Merge pull request #1630 from alphagov/inline-filter-fix

Stop nesting filter search results when dynamically loading