Add support for fog gem

[MOZGIII]

There is this gem, named fog, that provides access to different coulds. It supports managing not just storage, but also compute, dns and others.

But it does not support any personal clouds, like Yandex.Disk (or Google drive).

So, I'm suggesting you to implement Yandex.Disk fog storage.

This would be great cause gitlab uses fog in their backups system, and once we have Yandex.Disk with fog support, it would then be easy to backup gitlab with it (given it's very simple to integrate gitlabs backups with any fog-supported storage).