When unmarshalling manifests from JSON, check that the MediaType field
corresponds to the type that we are unmarshalling as. This makes sure
that when we retrieve a manifest from the manifest store, it will have
the same type as it was handled as before storing it in the manifest
store.
Signed-off-by: Owen W. Taylor <otaylor@fishsoup.net>
This makes content type sniffing cleaner. The document just needs to be
decoded into a manifest.Versioned structure. It's no longer a two-step
process.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
