By all accounts, Dzhokhar Tsarnaev, the younger of two brothers suspected of having perpetrated the Boston Marathon bombings, was a good kid, a bright young man and hardly the type of angry malcontent you’d expect of a terrorist. He graduated from Cambridge Rindge and Latin where he starred on the varsity wrestling team, and earned a city-funded $2,500 scholarship toward his tuition at UMass Dartmouth. One friend even characterized the 19-year-old as a guy who gave off “a good vibe.”