Adding option to sort a list by newest first.

I find myself adding gifs to a list and keep forgetting which one are
the new ones. So this adds a `--recent` flag to the list which allows me
to do just that.

Obligatory gif that made me smile ![Drop the bass](http://gifmesmile.com/data/published/03_2012/b328f72cc08454eb3349717912eaa4eb_pub.gif)