/**
* Retrieve Permission Groups, optionally specifying limiting criteria
* @param string agent_type (pp_group, bp_group, etc.)
* @param array args :
* - agent_type
* - cols
* - omit_ids
* - ids
* - where
* - require_meta_types
* - skip_meta_types
* - search
* @return array Permission Groups
*/
function pp_get_groups( $agent_type = 'pp_group', $args = array() )