remove buildah requirement for the libpod image library

if we snip the requirement to use a buildah const in the libpod image library,
we can save something on the order of 85 vendored files in consumers of the
the library.

Signed-off-by: baude <[email protected]>

Closes: #1054
Approved by: mheon

Author: baude

cmd/podman/commit.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/containers/image/manifest"
 	"github.com/pkg/errors"
 	"github.com/projectatomic/buildah"
 	"github.com/projectatomic/libpod/cmd/podman/libpodruntime"
@@ -83,7 +84,7 @@ func commitCmd(c *cli.Context) error {
 			return errors.Errorf("messages are only compatible with the docker image format (-f docker)")
 		}
 	case "docker":
-		mimeType = buildah.Dockerv2ImageManifest
+		mimeType = manifest.DockerV2Schema2MediaType
 	default:
 		return errors.Errorf("unrecognized image format %q", c.String("format"))
 	}

libpod/image/image.go

@@ -22,7 +22,6 @@ import (
 	"github.com/opencontainers/go-digest"
 	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
-	"github.com/projectatomic/buildah"
 	"github.com/projectatomic/libpod/libpod/common"
 	"github.com/projectatomic/libpod/libpod/driver"
 	"github.com/projectatomic/libpod/pkg/inspect"
@@ -940,7 +939,7 @@ func (i *Image) Containers() ([]string, error) {
 
 // Comment returns the Comment for an image depending on its ManifestType
 func (i *Image) Comment(ctx context.Context, manifestType string) (string, error) {
-	if manifestType == buildah.Dockerv2ImageManifest {
+	if manifestType == manifest.DockerV2Schema2MediaType {
 		imgRef, err := i.toImageRef(ctx)
 		if err != nil {
 			return "", errors.Wrapf(err, "unable to create image reference from image")