PROVIDENCE, R.I. — A playground spat between two little boys at the Hartford Park housing development Thursday led to a violent brawl among adults, who used their fists, a baseball bat and a knife to attack each other.After police broke up the fight, they arrested Michaela Vanover, 29, the mother of the 4-year-old boy, and Juan Irizarry, 26, the boyfriend of the mother of the 6-year-old boy for alleged assaults.Vanover had confronted the 6-year-old boy about a fight [...]