Support rclone API

[agritheory]

[batonac]

This is a great idea. Is this an implementation detail for #111 and a solution for #107?

[agritheory]

No, thought I had was that it was a way to get a minimal virtual drive set up. A (power) user could mount a folder on their machine and it would just sync. Support for Fuse could be separate.

[batonac]

Gotcha. Rclone supports mount as well as sync, so it seems like a reasonable way to cache files for local access as well.