Updated FEB 04, 2015 1:44a ETUFC 183 was supposed to go down as one of the biggest nights of the year with the return of former pound-for-pound king Anderson Silva and Nick Diaz, but now Silva's victory has been marred following positive drug tests for both fighters from the main event.The UFC said it was informed on Tuesday that Silva tested positive for Drostanolone metabolites in a pre-fight drug test administered...