0.16.0

• The [Build] section is now optional in .app.toml files. Applications are then listed by baur ls apps with the status Build Command Undefined builds can not be done.
• Build Inputs and Outputs definitions can now be included.
  An example include file can be created with baur init include. An include file can contain a BuildInput and a BuildOutput section.
  Include files can be included in an .app.toml file by referencing their path in the includes field.
  See https://github.com/simplesurance/baur-example for an example
• The .app.toml file and all files that are referenced in the includes field are now automatically included as BuildInputs of an application.
• The $APPNAME variable is additionally supported in the following fields of an .app.toml file:
  • Build.Output.File.Path
  • Build.Output.DockerImage.RegistryUpload.Repository
  • Build.Output.File.S3Upload.Bucket
  • Build.Output.DockerImage.idfile
• The configuration file version was increased to 2. To update from an previous baur version set config_version to 2 in your .baur.toml file.