Little did Sean O’Callaghan, Peter O’Mara and Richard Gleason know when they were sworn in as assistant state’s attorneys on the same day in 2005 that eight years later they would each tender resignations on the same day.The three former prosecutors took a leap in 2013 and left the stability of the state’s attorney’s office to form their own civil litigation firm, an area in which they had little experience.In the nearly four years since O’Mara, Gleason, O’Callaghan LLC was born …