Dockerize pipelines

[zbal]

Need a nice Dockerfile + ability to configure the workspace + various config via env var.

Issue:

• gotta keep it light
• gotta find a way to still allow misc commands (e.g. ansible) while not available by default in the container
  • either via doc to overload the repo
  • or by allowing this container to spawn ... other containers to let them run their own commands ...

[hunvreus]

Would be good to add at the same time a Heroku deploy button or similar methods of deployment. However, without a simple way to create/edit/remove pipelines and add files (e.g. Ansible playbooks) through the UI, it's close to useless. People can't easily manage files on a Heroku instance or container.

I guess we should start by at least allowing users to add/remove/edit pipelines through the UI (similar to what we were doing with devo.ps).