Manages a group's repository permissions.
$privileges = new Bitbucket\API\GroupPrivileges();
$privileges->setCredentials(new Http\Message\Authentication\BasicAuth($bb_user, $bb_pass));
$groups = $privileges->groups($account_name);
$groups = $privileges->repository($account_name, $repo_slug);
$group = $privileges->group($account_name, $repo_slug, $group_owner, $group_slug);
$repos = $privileges->repositories($account_name, $group_owner, $group_slug);
$privileges->grant($account_name, $repo_slug, $group_owner, $group_slug, 'read');
$privileges->delete($account_name, $repo_slug, $group_owner, $group_slug);