Use assertive not polite here

So the new result count is announced immediately rather than waiting for the user to move focus off of the checkbox they've just selected.
Merge pull request #55 from alphagov/use-aria-assertive

Use assertive not polite here
Add any_filters_applied filter

User research revealed that users were being conufsed by the big number at the top of the page when they initially landed on the finder, thinking it meant they had already completed a search when they hadn't.

This commit adds in a flag to the .to_hash of the result_set which tells us if any filters have been applied. Based on the value of this filter we can then show or not show the result count.
Reshuffle markup and add any_filters_applied flag

So that the status updates are still read and added, move the p.result-info into the mustache template and then wrap it in an 'any_filters_applied' flag which will only display it if the finder has had some results displayed.
Updtae js to replace the js-search-results-info text

Instead of looking for .result-info inside of js-search-results-info (which might not be on the page if there are no results), just replace that whole text.
Update cucumber test

On page load the page should no longer contain the number of cases