daemon: container ArchivePath and ExtractToDir

The following methods will deprecate the Copy method and introduce
two new, well-behaved methods for creating a tar archive of a resource
in a container and for extracting a tar archive into a directory in a
container.

Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)