By David Lawder WASHINGTON (Reuters) - Former Washington Mayor Marion Barry, jailed in 1991 for cocaine use only to reclaim his office and prominence in city politics, avoided another prison term on Thursday when a judge sentenced him to three years probation for failure to pay taxes. U.S. Magistrate Judge Deborah Robinson ordered Barry, now a city council member, to repay up to $246,000 in back taxes, plus penalties, and to comply with drug treatment and counseling requirements imposed by the U.S. probation office. Barry, 70, partly blamed his tax and financial woes for a relapse into drugs last fall....