Make container independent of network configuration

[fkraeutli]

Passing the IP address as an Env variable means it is difficult to take advantage of Docker networking features. Furthermore the port 8080 appears to be hardcoded, i.e. if the container is mapped to a port other than 8080 on the host machine, the 3M Editor stops to function.

As a quick workaround it would be good to also have the port configurable as an Env variable, but better would be to take advantage of Docker's networking functionality.