Al Sharpton, President Obama’s “go-to man on race” as described by Politico last year, is at it again. After riling up the nation over false narratives about Trayvon Martin and Michael Brown, Sharpton has found a case he can get behind where there appears to be little doubt this time that a white policeman, Michael Slager, brutally and unnecessarily shot to death an unarmed black man in South Carolina.