* Move multiple defaults from entrypoint script to cfg.lua files.
* Move remaining defaults from entrypoint script to cfg.lua files.
* Update postgres version in tests
* Register users with prosodyctl in tests
* Replace 'docker-compose' with 'docker compose'
Fixes#55 and fixes#56:
* Add environment variable HTTP_UPLOAD_FILE_SIZE_LIMIT for setting http_upload_file_size_limit
* Add environment variable HTTP_MAX_CONTENT_SIZE
* Add domain_http_upload to disco_items to support http_upload on some clients and if http_upload is not a subdomain
* Add environment variables for Database configuration.
* Install postgres and mysql dependencies.
* Test refactoring
* Run tests for prosody with postgres and also for prosody with sqlite.
* Add tests that check if postgres or sqlite is used.
