The logo of mobile app "Snapchat" is displayed on a tablet on January 2, 2014 in Paris. Hackers broke into Snapchat, the hugely popular mobile app, accessing the phone numbers and usernames of 4.6 million users and publishing them online, tech news website TechCrunch has announced.     AFP PHOTO / LIONEL BONAVENTURE        (Photo credit should read LIONEL BONAVENTURE/AFP/Getty Images)