By Jeffrey Heller JERUSALEM (Reuters) - An a**nymous U.S. official's reported description of Prime Minister Benjamin Netanyahu as a "chickenshit", or worthless coward, drew a sharp response on Wednesday from the Israeli leader - ** stranger to acrimony with the Obama administration. The American broadside, in an interview in The Atlantic magazine, followed a month of heated exchanges between the Netanyahu government and Washington over settlement-building in Israeli-annexed East Jerusalem, which Palestinians seek as the capital of a future state in the West Bank and Gaza Strip. ...