Change dash --> underscore for docker_network & docker_sandbox

[MIKE-ZW]

Because dashes are problematic for package naming in Java.

@lfpino: Do you remember what specific Java package naming problems occur with dashes?

[lfpino]

Sorry for the delay!

Actually, can you move everything onto a docker folder with two subfolders network and sandbox to make the package name changes as well? Right now it works because the name is package docker.<rest> but it can't be package docker-network.<rest> for instance

Should be straightforward.