Revert "Revert "Use the time now as a default from filter for upcoming announcements""

This reverts commit c047d1b75babfde185a1bb5b43e3d9a9e5f6394a.
Pass Rummager a Date, which it expects, not Time
Merge pull request #1642 from alphagov/fix_default_from_date_to_upcoming_stats_filter

Fix default from date to upcoming stats filter