Point to the new docker image

### Differences
* bumps to the 0.9.0 release
* generates sinopia config on first run via custom script
* can now be built directly with a Dockerfile, no preliminary step
* it is an automated build on the docker index

this replaces the [old image](https://registry.hub.docker.com/u/keyvanfatehi/docker-sinopia/) -- the old image has also been updated to 0.9.0 but it is not an automated build and will no longer be updated. (i will remove it on next release if I can). ideally, docker will allow us to convert repos to automated build repos that once weren't.