Fix: `grid` ARIA role should be on the `table`, not the container

- Feedback from James Craig - author of WAI-ARIA specification.
Fix: Keyboard navigation of the paging control

- Because DataTables is destroying and creating elements for the paging
  control, focus is lost when navigating via keyboard. This is a real
  pain when trying to operate DataTables that way! Fix is to refocus on
  the new element.