Extract services from existing docker-compose file

[saitho]

Instead of specifying the services in the project definition it should also be possible to specify an existing docker-compose file that is already used in the project source.

Example:

deployment:
  type: container
  service_file: ../../docker-compose.yml # relative path from the project configuration file

Mutually exclusive with services setting.

It will then extract the information that can currently be set in project definition from that file.