[FEATURE REQUEST] support for file versioning

## It would be super helpful to have file-versioning to enable rollback on overwritten files.

I am aware that the server can be configured to rename files for versioning, instead of overwriting, but it would be nice to have a management layer to provide UI-accessible version-control within a single file node.

Since the file-transfer library already manages uploads as chunks, the ideal solution would be a block/chunk level version controller such as [bup](https://bup.github.io/) or [restic](https://restic.net/).

### Unfortunately, Bup is not maintained, so you would need to fork it / rip it into your project, and Restic does not currently have a python interface, and does not provide native diff tools.

If you are inspired by the idea of a file-versioning feature, I would be open to collaborating or even prototyping an implementation, but of course that's a pretty huge feature for someone who is new to your code base.

#### P.S.
Thanks for your hard work, this project is really phenomenal, and you should be very proud!