Add a dockerfile

[mathieui]

It would be nice to have it available on the Docker hub as an automated build, too.

I have pushed the resulting docker image to my personal repo on docker hub to test and deploy BookBrowser for the meantime.

I run it using docker stack and traefik:

version: '3.3'

services:
  bookbrowser:
    image: mathieui/bookbrowser:latest
    networks:
      - default
      - web
    ports:
      - "8090"
    volumes:
      - /data/books:/books
    labels:
      - "traefik.backend=bookbrowser-app"
      - "traefik.docker.network=web"
      - "traefik.frontend.rule=Host:books.example.com"
      - "traefik.enable=true"
      - "traefik.port=8090"
      - "traefik.default.protocol=http"
      - "traefik.frontend.auth.basic=<user:password htpasswd payload>"

networks:
  web:
    external: true

[pgaskin]

Thanks for the contribution! I'll review it later this week when I have more time.

[pgaskin]

Looks good. Thanks!

P.S. I'll add this to the release script sometime soon.