Bug fixes and activating debugging for development

This debugging Release is getting us closer to a functional Hawthorn.1 image in Arnold:

• Activate easy creation of test users in development
• Use LMS and CMS hosts as site names for the LMS and CMS respectively
• Fix bug on the configuration of the email backend in development
• Fix activating requirejs debugging mode in development
• Add missing setting for Celery default queues

Make all settings configurable via environment variables

This Release adds configuration formatters on all settings so that they can all be set via environment variables.

This is because environment variables can only pass strings and some settings are expecting other types. Here are some examples of formatters we use:

• Booleans: bool
• Integers: int
• Dictionaries or lists: json.loads
• Dates: dateutil.parser.parse

Add mailcatcher, deactivate Celery and make settings more flexible

• Improve email settings to allow flexible configurations in each environment,
• Add mailcatcher to handle the emails sent by edxapp in fun-platform,
• Deactivate Celery to simplify development in fun-platform,
• Move environment variables to environment files,
• Allow formatting settings passed as environment variables and apply it for celery, mailcatcher and the database configurations,
• Fix "update_assets" in development Dockerfile to avoid the uninstalling/reinstalling that Open edX does by default.

Remove webpack stats from the statics target folder

There is no obvious reason to store webpack-stats.json files in the STATIC_ROOT tree.

It causes more problems than it solves as we need to manually copy it during deployment since it is not collected via collectstatics. Generating those files with update_assets at the project root seems a reasonnable choice.

First experimental release of an hawthorn.1 Docker image

This Release is the result of updating our Open edX images from ginkgo to hawthorn.1.

It is not functional and is intended for development and debugging work in Arnold.