[Feature Request] Support add folders from kobopatch.yaml

[bangedorrunt]

At the moment, kobopatch.yaml support files to transfer files to Kobo devices. I'd like to have folders support to transfer folders as well. That would be helpful in case I want to keep apps such as Plato and KoReader updated in sync with Kobo devices.

Example:

folders:

	src/plato: mnt/onboard/.add/plato
	src/koreader: mnt/onboard/.add/koreader