by Glenn CHAPMAN / with Rob Lever in Washington and Robin Millard in London Agence France Presse SAN FRANCISCO, United States (AFP) — Facebook chief Mark Zuckerberg vowed Wednesday to “step up” to fix problems at the social media giant, as it fights a snowballing scandal over the hijacking of personal data from millions of its users. “We have a responsibility to protect your data, and if we can’t then we don’t deserve to serve […]