Automatically delete download pictures after a period of time?

[Grafini]

Version of Variety you are using
0.8.5

Is your feature request related to a problem? Please describe.
Downloaded pictures take up an ever-growing amount of space. I have limited storage and would like to limit the amount of pictures (other than my favorites) that are stored locally at any one time.

Describe the solution you'd like
A setting to limit the amount of images stored in ~/.config/variety/Downloaded to a set amount of images or a set file size.

Additional context
Thanks for making this wonderful program!