Tidy up stats announcements table view

Various changes to make it more user-friendly:

* Re-order the columns to put "Release date" first
* Highlight the release date column to draw attention to the ordering
* Remove the "Display date" column and show the info in the title column
* Only highlight the publication cell for announcements without a publication
* List the organisations as a sentence, not as an HTML list
* Change the "Reset" link to read "Reset all fields" to be consistent with the
documents filter