How WhatsApp's billionaire CEO spent the year after the $19 billion Facebook acquisition

It's been exactly one year since Facebook acquired mobile messaging company WhatsApp for $19 billion.  The groundbreaking deal made both of the app's cofounders billionaires.  Originally from Kiev, Ukraine, CEO Jan Koum moved with his family to the US when he was 16 years old. The family struggled and lived on welfare and food stamps. With an estimated net worth of $6.8 billion, Koum has certainly come a long way since his food stamp days.  In a somewhat symbolic move, Koum signed the paper...