A repeat offender convicted of sexually assaulting a woman in the bathroom of a Gramercy bar in 2015 was sentenced on Thursday to spend at least two decades in prison. A judge sentenced ex-convict Rodney Stover, 49, to 20 years-to-life for an April 11, 2015 attack, when he violently sexually assaulted a 23-year-old woman in the bathroom of Turnmill bar, at 119 E. 27th St. between…