By Joshua Schneyer and Brian Grow NEW YORK/ATLANTA (Reuters) - Billionaire Russian businessman Gennady Timchenko, a long-time associate of Russian President Vladimir Putin, plans to seek U.S. government-backed funding to buy luxury aircraft, Reuters has learned. To smooth the path for financial backing from the U.S. Export-Import Bank and allay possible U.S. government concerns about him, Timchenko hired lobbyists from powerhouse Washington law firm Patton Boggs, according to emails and documents viewed by Reuters. ...