add casync

[enkore]

See also http://0pointer.net/blog/casync-a-tool-for-distributing-file-system-images.html

[fd0]

Thanks for the hint. I don't think that casync qualifies. As far as I understood it, it's more of a distributed rsync with blob storage. It can be used for backups, but that's not the primary use case. We also don't list other things such as unison, rsync, cp, tar etc.

I'm closing this for now, please feel free to add comments. Thanks!