WASHINGTON (Reuters) - Jack Lew, President Barack Obama's pick to be U.S. treasury secretary, on Wednesday defused heated questions from lawmakers about his work at Citigroup and managed to find common ground with critics over the need for tax reform. At a hearing on his nomination, Republicans blasted Lew with questions about his investment in a fund linked to the Cayman Islands and his time at Citigroup, especially a $940,000 bonus he received just before the bank got a taxpayer-funded bailout. ...