More Flexibility (and Docs)

[andrewcooke]

Hi, this looks great, but when I tried to use it I realised that I needed --copy-dirlinks in there too. And I imagine other people will want other features. So it struck me that a way to pass arbitrary options down to rsync would be nice.

Also, it would be good if the docs included some reference to your python-rotate-backups project - it wasn't until I read that that I understood what was happening.