ivatar / libravatar as docker image

This is ivatar as a docker image. The image is freshly built every month from the ivatar repository at git.linux-kernel.at.

I couldn't deeply test the image, so please use it with caution.

How to use this image

docker run --name ivatar -p 8080:8080 -d registry.gudd-it.de/bastian/ivatar-docker

Please be aware that this will not persist any data.

Variable	Description	Default from config.py
`SITE_NAME`		`libravatar`
`SECURE_BASE_URL`		`https://avatars.linux-kernel.at/avatar/`
`BASE_URL`		`http://avatars.linux-kernel.at/avatar/`
`EMAIL_BACKEND`		-
`IVATAR_MAILGUN_API_KEY`		-
`IVATAR_MAILGUN_SENDER_DOMAIN`		-
`SERVER_EMAIL`		`ivatar@mg.linux-kernel.at`
`DEFAULT_FROM_EMAIL`		`ivatar@mg.linux-kernel.at`
`MYSQL_DATABASE`		-
`MYSQL_USER`		-
`MYSQL_PASSWORD`		-
`POSTGRESQL_DATABASE`		-
`POSTGRESQL_USER`		-
`POSTGRESQL_PASSWORD`		-