fixes #1881 - adding auto refresh button to dashboard

Fixes #10929 - Add removed widgets to dashboard

This commit allows users to re-add widgets. At this point it's only
possible to recover removed widgets by clicking on "Reset to default".

To do this I populate the 'Add widgets' list by getting a diff
between the current widgets and the available ones. The code calls any...

Fixes #8106 - Dashboard rewrite to allow better customization

fixes #5345 - customizable dashboard