The logo of blockchain company Ripple is seen at the SIBOS banking and financial conference in Toronto, Ontario, Canada October 19, 2017. REUTERS/Chris Helgren/File Photo Purchase Licensing Rights, opens new tabAug 7 (Reuters) - Ripple will buy stablecoin payments platform Rail for $200 million, the company said on Thursday, weeks after U.S. President Donald Trump signed a law that raised expectations cryptocurrency tokens are about to enter the mainstream.Ripple, a crypto company that is closel...