Modal sosial dan kekerasan kolektif geng nongkrong di permukiman kumuh perkotaan : studi kasus geng nongkrong Kota Paris dan Caplin di Kecamatan Johar Baru, Jakarta Pusat = Social capital and collective violence of youth street gangs in the urban slums : case study of social capital of Kota Paris and Caplin youth street gangs in the Johar Baru Subdistrict Center Jakarta