Add aria-live and get keyboard focus to follow you

Add tabindex="-1" to the right elements so we can send focus there but
you can't tab to them. Add aria-live so that when the content changes
users are polietly informed.
Merge pull request #19 from alphagov/keyboards

Add aria-live and get keyboard focus to follow you
Add analytics tracking on browse pages

Return defereds on all the methods called in the popState method. Add a
new done to those defereds to send analytics data.

Move the pushState to after render of the new data on navigation and add
analytics tracking next to it. After render feels better just incase
they abort during render.