Add 'kpod images' and 'kpod rmi' commands

'kpod images' lists all images on a system.  'kpod rmi' removes
one or more images from a system.  The images will not be removed
if they are associated with a running container, unless the -f
option is used

Signed-off-by: Ryan Cole <rcyoalne@gmail.com>

cmd/kpod/common.go

@@ -1,7 +1,11 @@
 package main
 
 import (
+	"encoding/json"
+	"fmt"
 	"io"
+	"strings"
+	"time"
 
 	cp "github.com/containers/image/copy"
 	is "github.com/containers/image/storage"
@@ -11,10 +15,21 @@ import (
 	"github.com/urfave/cli"
 )
 
+type imageMetadata struct {
+	Tag            string              `json:"tag"`
+	CreatedTime    time.Time           `json:"created-time"`
+	ID             string              `json:"id"`
+	Blobs          []types.BlobInfo    `json:"blob-list"`
+	Layers         map[string][]string `json:"layers"`
+	SignatureSizes []string            `json:"signature-sizes"`
+}
+
 func getStore(c *cli.Context) (storage.Store, error) {
 	options := storage.DefaultStoreOptions
-	if c.GlobalIsSet("root") || c.GlobalIsSet("runroot") {
+	if c.GlobalIsSet("root") {
 		options.GraphRoot = c.GlobalString("root")
+	}
+	if c.GlobalIsSet("runroot") {
 		options.RunRoot = c.GlobalString("runroot")
 	}
 
@@ -67,3 +82,34 @@ func getSystemContext(signaturePolicyPath string) *types.SystemContext {
 	}
 	return sc
 }
+
+func parseMetadata(image storage.Image) (imageMetadata, error) {
+	var im imageMetadata
+
+	dec := json.NewDecoder(strings.NewReader(image.Metadata))
+	if err := dec.Decode(&im); err != nil {
+		return imageMetadata{}, err
+	}
+	return im, nil
+}
+
+func getSize(image storage.Image, store storage.Store) (int64, error) {
+
+	is.Transport.SetStore(store)
+	storeRef, err := is.Transport.ParseStoreReference(store, "@"+image.ID)
+	if err != nil {
+		fmt.Println(err)
+		return -1, err
+	}
+	img, err := storeRef.NewImage(nil)
+	if err != nil {
+		fmt.Println("Error with NewImage")
+		return -1, err
+	}
+	imgSize, err := img.Size()
+	if err != nil {
+		fmt.Println("Error getting size")
+		return -1, err
+	}
+	return imgSize, nil
+}