By ANA LEY and MARK BONAMO NYTimes News Service Violent clashes between demonstrators and federal agents erupted early Friday outside an immigration detention center in Newark, New Jersey, after nearly a week of protests over living conditions at the facility. Just past midnight, about 50 activists convened in front of about 30 federal agents. A group of officers charged into the crowd, and several protesters were pushed to the ground as officers sprayed a chemical irritant.