SACRAMENTO, Calif., April 19 (Reuters) - California peace activist Cindy Sheehan has agreed to meet with Internal Revenue Service agents seeking to collect back taxes she refuses to pay as a protest of U.S. wars, but she vowed on Thursday to persist in her tax boycott. Sheehan, whose son Casey was killed in action in Iraq while serving in the U.S. Army in 2004, appeared before a federal judge as the government sought a court order requiring her to answer an IRS collection summons seeking information about assets that could be used to satisfy her tax liability. The 54-year-old activist,...