Etcd configuration

We'd like to inject the etcd configuration via cli args. But there is still a supervisor in the docker container. So it's time to remove it and link a redis container.

* Inject etcd configuration via cli args
* Overwrite redis configuration via env vars from docker links
This is necessary to access the options. See https://github.com/giantswarm/hipache/blob/etcd-configuration/lib/config/config.js#L22