func (m *Manifest) SetSuppGroups(groups []int) error {
	if m.manifest.App == nil {
		m.manifest.App = newManifestApp()
	}
	m.manifest.App.SupplementaryGIDs = groups
	return m.save()
}
SetSuppGroups sets the groups the pod will run as in the untarred ACI
stored at a.CurrentACIPath.
package appc