If you saw the last two films Robert Redford directed — 2007’s “Lions for Lambs” and 2010’s “The Conspirator” — you likely weren’t surprised to hear that his latest, “The Company You Keep,” centers on political radicals. But you might be surprised to discover that one of Hollywood’s best-known liberals has made a film about 1960s anti-war militants that doesn’t attempt to whitewash their many crimes.