Signed-off-by: Christy Perez <christy@linux.vnet.ibm.com>

Enable inspection (aka "shallow pull") of images' manifest info, and
also the creation of manifest lists (aka "fat manifests").

The workflow for creating a manifest list will be:

`docker manifest create new-list-ref-name image-ref [image-ref...]`
`docker manifest annotate new-list-ref-name image-ref --os linux --arch
arm`
`docker manifest push new-list-ref-name`

The annotate step is optional. Most architectures are fine by default.

There is also a `manifest inspect` command to allow for a "shallow pull"
of an image's manifest: `docker manifest inspect
manifest-or-manifest_list`.

To be more in line with the existing external manifest tool, there is
also a `-v` option for inspect that will show information depending on
what the reference maps to (list or single manifest).

Signed-off-by: Christy Perez <christy@linux.vnet.ibm.com>
Signed-off-by: Daniel Nephin <dnephin@docker.com>

create, annotate, & push

Signed-off-by: Christy Perez <christy@linux.vnet.ibm.com>
Signed-off-by: Christopher Jones <tophj@linux.vnet.ibm.com>

Signed-off-by: Christy Norman Perez <christy@linux.vnet.ibm.com>