By Alexei Oreskovic SAN FRANCISCO (Reuters) – Facebook Inc is launching a mobile app that gives users in Zambia free access to a handful of online services on mobile phones, broadening an effort to boost Internet usage in underdeveloped countries. The Internet.org app will offer, in partnership with wireless operator Airtel , more than a dozen services including online encyclopedia Wikipedia, websites devoted to weather, job listings and health information, as well as Facebooks own social network and messaging service.