Have directories, files etc depend on zfs datasets

[fkusei]

Probably needs #648 first, so we don't have to add zfs stuff to all items.

[fkusei]

If we don't want to wait for #648, i'll be happy to submit a pull request changing all the items to add the dependency.

[trehn]

keep in mind that this might cause duplicate dependency errors for existing users who set these deps themselves, so this might have to wait for 5.0 (which we should do soon)

[fkusei]

Will create a PR for that. But yea, that'll be another one for 5.0.0.