Upgrade site and modules to Django 2.2. Remove and replace obsolete
functionality with current equivalents. Update requirements to latest
versions where possible. Remove unused dependencies.
* developers can use --target symposion_dev to get a responsive site
that reads from their homedir and reacts to changed files instantly
* without a specified target the default is to build the prod image,
which is identical except for running uwsgi instead of the django
built-in server
* Enable debug when running in a developer's test environment
* Remove the makemigrations script and dockerfile
* Adds an env variable to .env to turn on dev mode
* Uses the inbuilt django auth rather than saml when in dev mode
* For laziness, re-uses the admin login form for the non-admin login
make_dev_container now comes up ready to be logged into by any
user. No non-admin users are preconfigured; but you can add one at
http://localhost:28000/admin/auth/user/add/, log out, and then hit
http://localhost:28000/ to log in as the new user.
* Adds a laptop-mode-env file which docker can read env variables from
* Adds a Dockerfile.makemigrations; mostly identical to the main
Dockerfile. Important difference: instead of the source being copied
into the docker image at build time, it's mounted from the local
machine at run time.
* Adds a makemigrations shell script which builds an imagine using the
Dockefile.makemigrations and then uses it to run makemigrations
* Because the source is mounted from the local machine, any new
migrations created are dumped in the developer's git checkout ready
for adding to git.
Rename .env -> docker/laptop-mode-env
