Update docker-compose for Zanata 4.2+

[seanf]

Based on #20 and parts of https://github.com/jurikolo/zanata/blob/3906624e35b5aa8fae355d3e305f4e226afa6807/docker-compose.yml.

This docker-compose file uses v2.1 format, which is available in Docker 1.13.1+ (Fedora 26+). https://docs.docker.com/compose/compose-file/compose-versioning/

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Reviewed 2 of 2 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable

[tholu]

Can you add those variables to the .env file (perhaps commented)?

ZANATA_DAEMON_MODE=
ZANATA_MAIL_HOST=
ZANATA_MAIL_PORT=
ZANATA_MAIL_USERNAME=
ZANATA_MAIL_PASSWORD=

[seanf]

@tholu Can you elaborate? I don't think putting them in the .env file file would do anything by itself, because "Environment variables defined in the .env file are not automatically visible inside containers." - https://docs.docker.com/compose/env-file/#compose-file-and-cli-variables

I think it would be best to tackle these extras in a separate pull request.

[seanf]

We've done a bit of smoke testing on this, but, as usual, let us know if there's a problem with the docker images/config.

Thanks for the contributions @SlavikZ and @jurikolo.

[tholu]

@seanf Of course they would have to be provided in the docker-compose.yml file as well, right now it's not immediately clear from documentation, that these can be configured at all.

  environment:
      - MAIL_HOST=${ZANATA_MAIL_HOST}
      - MAIL_PORT=${ZANATA_MAIL_PORT}
      - MAIL_USERNAME=${ZANATA_MAIL_USERNAME}
      - MAIL_PASSWORD=${ZANATA_MAIL_PASSWORD}
      - [...]