Docker 적용

순서
1. 장고 & Nginx, Gunicorn
2. Pipenv 대응
3. Backend, Frontend 통합

Nginx 설정 중 Upstream 등에 대한 설명
https://opentutorials.org/module/384/4328

Communication between multiple docker-compose projects (networks option)
https://stackoverflow.com/a/48024244