Last month, a Queens kindergartener was handcuffed after a temper tantrum at PS 81, prompting his parents to threaten a lawsuit. Now a lawyer representing Dennis Rivera and his parents reveals they are filing a notice of claim against the city for $15 million. According to the notice, Rivera, who the Daily News reports as suffering from "speech problems, attention deficit disorder and asthma," suffered injuries to his wrists as well as psychological and emotional......