Add ability to sort dashboard by modified date
Add ability to sort dashboard by modified date

This only implemented the backend,
so you can pass a GET arg to it to have it sort.

The goal will be to have a proper UI for this after the UI refactor,
but I want this now :)

rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org