snapshots: UI improvements

Created by: mray

Looking at a screenshot of the current "snapshots" module a few things came to mind:

1. Add snapshot size info

When deleting snapshots it might be very interesting how much space is gained by doing so. I'd put the info right next to the delete button.

entries listed like this:

would reflect the specific nature of the set much better. The long date format could remain a small gray sidenote.

What is the number good for? I don't see a possible use for it, other than confusion about the missing intermediate steps.