[18.06] Register OCI image media types

[thaJeztah]

OCI types are backwards compatible with Docker manifest types, however the media types must be registered.

cherry picked from commit c4f0515 (moby#37359); no conflicts. cherry-pick was clean

[thaJeztah]

ping @tonistiigi @dmcgowan PTAL

[tonistiigi]

LGTM

[thaJeztah]

Hm, Power and Z seem to have DNS issues;

20:26:48 W: Failed to fetch http://cdn-fastly.deb.debian.org/debian/dists/stretch/InRelease  Could not resolve 'cdn-fastly.deb.debian.org'
20:26:48 W: Failed to fetch http://security.debian.org/debian-security/dists/stretch/updates/InRelease  Could not resolve 'security.debian.org'
20:26:48 W: Failed to fetch http://cdn-fastly.deb.debian.org/debian/dists/stretch-updates/InRelease  Could not resolve 'cdn-fastly.deb.debian.org'
20:26:48 W: Some index files failed to download. They have been ignored, or old ones used instead.
20:26:48 Reading package lists...
20:26:48 Building dependency tree...
20:26:48 Reading state information...
20:26:48 E: Unable to locate package libnet-dev
20:26:48 E: Unable to locate package libprotobuf-c0-dev
20:26:48 E: Unable to locate package libprotobuf-dev
20:26:48 E: Unable to locate package libnl-3-dev
20:26:48 E: Unable to locate package libcap-dev
20:26:48 E: Unable to locate package protobuf-compiler
20:26:48 E: Unable to locate package protobuf-c-compiler
20:26:48 E: Unable to locate package python-protobuf

[dmcgowan]

LGTM