Propogate tag as a functional argument into the notification system to attach

tags to manifest push and pull event notifications.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>

registry.go

@@ -58,6 +58,18 @@ type ManifestServiceOption interface {
 	Apply(ManifestService) error
 }
 
+// WithTag allows a tag to be passed into Put
+func WithTag(tag string) ManifestServiceOption {
+	return WithTagOption{tag}
+}
+
+type WithTagOption struct{ Tag string }
+
+func (o WithTagOption) Apply(m ManifestService) error {
+	// no implementation
+	return nil
+}
+
 // Repository is a named collection of manifests and layers.
 type Repository interface {
 	// Named returns the name of the repository.