Lovely-pytest-docker

- make auto generated project names compatible with docker-compose 2.5

- add support for `docker-compose stop`
- allow to set the timeout and retry interval when waiting for services
- added explicit dependency to six, which is no more required in newer pytest versions

- explicitly set the project-directory in compose executors to allow older
compose versions to find ".env" files
see https://docs.docker.com/compose/environment-variables/#the-env-file

- added url_checker method to create an url_checker for a specific path

- added ``docker_services_project_name`` fixture in order to override the container
name prefix for started services.

- python 2 runtime compatibility