Backup Versioning

[jwink3101 (Justin Winokur)]

@ncw

BTW rclone will be doing atomic transfers to local, ftp, sftp in v1.63. This is upload to tempname and rename to actual name when complete.

I just tested this and it doesn't work with crypt wrapping local (and presumably (S)FTP). That is unfortunate but I guess I'll leave that in dfb.