godeps: update vmware/govmomi to v0.20 release

vendor/github.com/vmware/govmomi/object/common.go

@@ -100,6 +100,7 @@ func (c Common) ObjectName(ctx context.Context) (string, error) {
 	return n.Name, nil
 }
 
+// Properties is a wrapper for property.DefaultCollector().RetrieveOne()
 func (c Common) Properties(ctx context.Context, r types.ManagedObjectReference, ps []string, dst interface{}) error {
 	return property.DefaultCollector(c.c).RetrieveOne(ctx, r, ps, dst)
 }
@@ -130,3 +131,14 @@ func (c Common) Rename(ctx context.Context, name string) (*Task, error) {
 
 	return NewTask(c.c, res.Returnval), nil
 }
+
+func (c Common) SetCustomValue(ctx context.Context, key string, value string) error {
+	req := types.SetCustomValue{
+		This:  c.Reference(),
+		Key:   key,
+		Value: value,
+	}
+
+	_, err := methods.SetCustomValue(ctx, c.c, &req)
+	return err
+}