Max Schireson had a nice year as a full-time family man. He helped plan his eldest daughter's bat mitzvah. He took ski instructor classes with his 15-year-old son. He was the room parent for his younger daughter's class. He spent a weekend away with his wife. But now the former MongoDB CEO, who resigned from the software heavyweight last August to spend more time with his family, has joined the Massachusetts-based venture capital firm Battery Ventures as an executive in residence.