Rsnapshot fix cron and unattended-upgrades

This was supposed to be just the cronjob addition for the rsnapshot role.  But I seem to have managed to add all the unattended upgrades stuff into it as well.  Sorry about that.  If you can merge all this lot in as well,  I'll make sure the next one is just the one commit that I actually wanted to add.
Where is this file? I don't see it checked in.