The social messaging app Wiper added a built-in bitcoin wallet last month, enabling instant transactions among contacts, as well as basic wallet functionality. Bitcoin integrated Wiper is most often compared to SnapChat, but unlike that popular app, it isn't entirely focused on vanishing messages. Wiper, unlike SnapChat, doesn't delete messages by default. Instead, users can decide when to delete messages from both their phones and the recipient's phone. Adding a bitcoin wallet in the app couldn't be simpler. Hit a few buttons, set a four digit pass code, write down the backup phrase and you are good to go. It …