Move Manifest type into storage package

This changeset move the Manifest type into the storage package to make the type
accessible to client and registry without import cycles. The structure of the
manifest was also changed to accuratle reflect the stages of the signing
process. A straw man Manifest.Sign method has been added to start testing this
concept out but will probably be accompanied by the more import
SignedManifest.Verify method as the security model develops.

This is probably the start of a concerted effort to consolidate types across
the client and server portions of the code base but we may want to see how such
a handy type, like the Manifest and SignedManifest, would work in docker core.

images.go

@@ -2,76 +2,13 @@ package registry
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
 
-	"github.com/docker/docker-registry/digest"
+	"github.com/docker/docker-registry/storage"
 	"github.com/gorilla/handlers"
 )
 
-// ImageManifest defines the structure of an image manifest
-type ImageManifest struct {
-	// Name is the name of the image's repository
-	Name string `json:"name"`
-
-	// Tag is the tag of the image specified by this manifest
-	Tag string `json:"tag"`
-
-	// Architecture is the host architecture on which this image is intended to
-	// run
-	Architecture string `json:"architecture"`
-
-	// FSLayers is a list of filesystem layer blobSums contained in this image
-	FSLayers []FSLayer `json:"fsLayers"`
-
-	// History is a list of unstructured historical data for v1 compatibility
-	History []ManifestHistory `json:"history"`
-
-	// SchemaVersion is the image manifest schema that this image follows
-	SchemaVersion int `json:"schemaVersion"`
-
-	// Raw is the byte representation of the ImageManifest, used for signature
-	// verification
-	Raw []byte `json:"-"`
-}
-
-// imageManifest is used to avoid recursion in unmarshaling
-type imageManifest ImageManifest
-
-// UnmarshalJSON populates a new ImageManifest struct from JSON data.
-func (m *ImageManifest) UnmarshalJSON(b []byte) error {
-	var manifest imageManifest
-	err := json.Unmarshal(b, &manifest)
-	if err != nil {
-		return err
-	}
-
-	*m = ImageManifest(manifest)
-	m.Raw = b
-	return nil
-}
-
-// FSLayer is a container struct for BlobSums defined in an image manifest
-type FSLayer struct {
-	// BlobSum is the tarsum of the referenced filesystem image layer
-	BlobSum digest.Digest `json:"blobSum"`
-}
-
-// ManifestHistory stores unstructured v1 compatibility information
-type ManifestHistory struct {
-	// V1Compatibility is the raw v1 compatibility information
-	V1Compatibility string `json:"v1Compatibility"`
-}
-
-// Checksum is a container struct for an image checksum
-type Checksum struct {
-	// HashAlgorithm is the algorithm used to compute the checksum
-	// Supported values: md5, sha1, sha256, sha512
-	HashAlgorithm string
-
-	// Sum is the actual checksum value for the given HashAlgorithm
-	Sum string
-}
-
 // imageManifestDispatcher takes the request context and builds the
 // appropriate handler for handling image manifest requests.
 func imageManifestDispatcher(ctx *Context, r *http.Request) http.Handler {