Tesla CEO Elon Musk made a memorable appearance at former President Trump's campaign rally in Butler, Pennsylvania, on Saturday – a rare appearance for the tech entrepreneur.  Wearing a black "Make America Great Again" hat and a T-shirt reading "Occupy Mars," Musk appeared on stage shortly after Trump made his own remarks before a massive crowd of 60,000 supporters. The rally was held at the same site where Trump was shot by gunman Thomas Matthew Crooks on July...