Tutor

- [Feature] Add support for simple, YAML-based plugins.
- 💥[Improvement] The output of `plugins list` now includes plugin version numbers.

- [Improvement] Explicitly point to docker.io images, when necessary, for [podman](https://podman.io/) compatibility.

- [Bugfix] Fix OAuth authentication in dev mode.
- [Improvement] Upgrade to the 3.7 docker-compose syntax.
- [Improvement] The `dev runserver` command can now be run for just any service.
- 💥[Feature] `dev run/exec` commands now support generic options which are passed to docker-compose. Consequently, defining the `TUTOR_EDX_PLATFORM_PATH` environment variable no longer works. Instead, users are encouraged to explicitly pass the `-v` option, define a command alias or create a `docker-compose.override.yml` file.

- [Improvement] Make it possible to override the project name in development mode.
- [Bugfix] Fix user switching in development mode.
- [Bugfix] Fix "k8s quickstart" crash.

- [Security] Apply django 1.11.21 -> 1.11.27 security patches.
- [Bugfix] Fix running dev image with `sudo`.
- [Improvement] Add `cms/lms-env-features` patches (276).
- [Feature] Add plugin subcommands.
- 💥[Improvement] Move ``-r/--root`` option to parent command level.
- [Bugfix] Fix course about page visibility.
- [Improvement] Print gunicorn access logs in the console.
- 💥[Improvement] Get rid of the `indexcourses` and `portainer` command (269).

- [Improvement] Add `k8s-deployments-nginx-volume-mounts` patch.
- [Bugfix] Fix running forum locally when both Elasticsearch and MongoDB are not activated (266).
- [Bugfix] Fix MongoDB URL in the forum when running a separate service (267).
- 💥[Improvement] Better `dev` commands, with dedicated development docker image. One of the consequences is that the `dev watchthemes` command is replaced by `dev run lms watchthemes`.
- [Improvement] `images` commands now accept multiple `image` arguments.