add logging and comments to db engine
add logging and comments to db engine

zachgersh/atc,pivotal-devin-fallak/atc,simonjjones/atc,savaki/atc,savaki/atc,simonjjones/atc,zachgersh/atc,simonjjones/atc,utako/atc,zachgersh/atc,savaki/atc,utako/atc,pivotal-devin-fallak/atc,zachgersh/atc,pivotal-devin-fallak/atc,utako/atc