PHILADELPHIA (Reuters) - Michael Berg, whose son Nick was beheaded in Iraq in 2004, said on Thursday he felt no sense of relief at the killing of the al Qaeda in Iraq leader blamed for his son's death. Asked what would give him satisfaction, Berg, an anti-war activist and candidate for U.S. Congress, said: "The end of the war and getting rid of George Bush." The United States said its aircraft killed Abu Musab al-Zarqawi, the insurgent leader who masterminded the death of hundreds in suicide bombings and was blamed for the videotaped beheading of Nick Berg, a U.S. contractor,...