HARARE (Reuters) - Emmerson Mnangagwa will cap a stunning political comeback on Friday when he is sworn in as Zimbabwe’s president, bringing the final curtain down on the 37-year rule of Robert Mugabe. Even though most Zimbabweans are jubilant at the exit of 93-year-old Mugabe, who had led Zimbabwe from independence in 1980, the army’s detention and rough treatment of pro-Mugabe ministers is worrying human rights groups.