Move libkpod/image libkpod/layer to libpod/images and libpod/layers

Begin moving image and layer handling out of libkpod into libpod.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

libpod/images/rmi.go

@@ -0,0 +1,35 @@
+package images
+
+import (
+	"github.com/containers/storage"
+	"github.com/pkg/errors"
+)
+
+// UntagImage removes the tag from the given image
+func UntagImage(store storage.Store, image *storage.Image, imgArg string) (string, error) {
+	// Remove name from image.Names and set the new names
+	newNames := []string{}
+	removedName := ""
+	for _, name := range image.Names {
+		if MatchesReference(name, imgArg) {
+			removedName = name
+			continue
+		}
+		newNames = append(newNames, name)
+	}
+	if removedName != "" {
+		if err := store.SetNames(image.ID, newNames); err != nil {
+			return "", errors.Wrapf(err, "error removing name %q from image %q", removedName, image.ID)
+		}
+	}
+	return removedName, nil
+}
+
+// RemoveImage removes the given image from storage
+func RemoveImage(image *storage.Image, store storage.Store) (string, error) {
+	_, err := store.DeleteImage(image.ID, true)
+	if err != nil {
+		return "", errors.Wrapf(err, "could not remove image %q", image.ID)
+	}
+	return image.ID, nil
+}