If a bookmark is edited to have a different URL, mark it as available for caching again

[blakewatson]

What I said

[blakewatson]

You can kind of do this with the re-cache button. I will leave this issue open for now though because there are probably other fixes that need to happen. Off the top of my head, I'm thinking about the background archiver. It would be nice if it could realize that a URL changed and make it available for archival again.