Allows linking to multiple snapshots within the same snapshotter.
Adds support for using slash to separate content as well for consistency.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Marks and sweeps unreferenced objects.
Add snapshot cleanup to metadata.
Add content garbage collection
Add dirty flags for snapshotters and content store which
are set on deletion and used during the next garbage collection.
Cleanup content store backend when content metadata is removed.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
