Rationale:
1. building production stack on the same machine with local doesn't lead to conflicts anymore;
2. production and local service images are now clearly distinguished by name.
* Update generated project's .gitignore
* Post-gen gitignore .env/ and .env
* Fix linesep between gitignored entries
* Persist `.env/**/*` files into cookiecutter-django's VCS
* Rename .env/ to .envs/
* Reference the newly created .envs/**/.* files in local.yml
* Reference the newly created .envs/**/.* files in production.yml
* Delete .env.example
* Refactor post-gen-project.py
Closes#1299.
* Implement production-dotenv-files-to-dotenv-file merge script
* Create shared PyCharm Run Configuration for the automation script
* Randomize POSTGRES_PASSWORD in ./envs/(.local|.production)/.postgres
* Default POSTGRES_PASSWORD and POSTGRES_USER to random values
* Fix jinja linebreaks in local.yml
* Spaces in production.yml
* Fix post-merge leftovers & set DJANGO_ADMIN_URL automatically
* Prettify here and there
* Fix FileNotFoundError
* Leave a TODO in post_gen_hook.py
* Introduce keep_local_envs_in_vcs option
* Remove envs when not opted for
* Inline pre_gen_project.py if-condition
* Get rid of PROJECT_DIR_PATH in post_gen_project.py
* Clean up the docs
* Match copyright notices
* Document envs ins and outs
* Re-organize compose/ into environment-specific file groups
Closes#1316.
* Commit missing files
That was weird: git failed to commit one specific folder previously
* Introduce development-time Celery services
Closes#1225.
* Re-order django and postgres services in production.yml
* Switch local service extension tactics
* Fix celery services inheriting ports from the django's
