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”
Merge pull request #1630 from alphagov/inline-filter-fix

Stop nesting filter search results when dynamically loading