Make history on dashboard with papertrail in descending order

Somewhat similar to https://github.com/sferik/rails_admin/pull/1147, but with PaperTrail history this time.

Also duplicates compatibility with paper_trail 3 https://github.com/sferik/rails_admin/pull/1831 as I've just discovered, so please take a look. I needed to implement this compatibility for testing purposes, because of dependencies. See my comment in commit about airblade/paper_trail#250.