By Stella Mapenzauswa LUSAKA (Reuters) – Informal currency trader Jabulani Lungu thinks Zambia’s ruling Patriotic Front has had its chance, and he hopes this week’s general elections will bring in a new party to steer the economy out of a slump. Like many other Zambians, Lungu, who is not related to President Edgar Lungu, is worried about rising food and transport costs, unemployment, chronic…