add support for opencontainers meta labels

pkg/types/image_meta.go

@@ -0,0 +1,14 @@
+package types
+
+type ImageMeta interface {
+	Authors() string
+	Created() string
+	Description() string
+	Documentation() string
+	Licenses() string
+	Revision() string
+	Source() string
+	Title() string
+	Url() string
+	Version() string
+}

pkg/types/report.go

@@ -20,4 +20,6 @@ type ContainerReport interface {
 	ImageName() string
 	Error() string
 	State() string
+	Before() ImageMeta
+	After() ImageMeta
 }