refs #4985 Improve Dashboard / Datatables UI

Each dashboard widget shows footer icons, pager, ... but they are usually rarely used. Especially since we store changes in the database and apply them when opening the dashboard again. Therefore we want to hide the widget footer by default but give users the possibility to "expand" the footer. Some reports that provide further controls should be able to add controls to this by default hidden footer to hide complexity. It's up to each report to define useful default values.

Also made the dataTable and All Websites Dashboard look nicer. For instance removed some borders.