WASHINGTON — Booz Allen Hamilton, one of the 10 largest U.S. defense contractors, launched a $100 million venture capital fund to invest in fledgling companies creating promising new technology. The fund announced Wednesday, dubbed Booz Allen Ventures, will concentrate on bankrolling early-stage firms working on cutting-edge technology, and help them find ways to get those innovations into the field for use. Brian MacCarthy, vice president of tech scouting and ventures at Booz Allen, said in a