When we started the project. The file that contained configuration needed to build a bundle was called the duffle.toml file. We also decided to use viper to support json, toml, and yaml file types. We later had a conversation around standardizing on duffle.json. I don't recall what the end result was. Are we still supporting all three formats or did we decide to standardize on .json across the board? cc/ @carolynvs @itowlson