action to import group for Customer import by name
add static function searchByName to Group Class :
	/**
	  * Light back office search for Group
	  *
	  * @param integer $id_lang Language ID
	  * @param string $query Searched string
	  * @param boolean $unrestricted allows search without lang and includes first group and exact match
	  * @return array Corresponding groupes
	  */
	public static function searchByName($id_lang, $query, $unrestricted = false)