Changing deployment patterns for more generalised use cases

Created by: almereyda

This PR implements the following changes and is based on cowboy coding, plus elaborations in private chat channels:

• change lb_web network name to frontend-web ⚠️ note this is a breaking change for all service recipies which depend on this name space ⚠️
• reference the docker binary by absolute paths used in the .deb package 💡 using other ways of invoking the library, i.e. via its global alias in PATH may generalise deployment scenarios here 💡
• do not assume a www subdomain for every service deployment and require explicit configuration via docker-compose.yml and associated environment or env_files settings. This affects the VIRTUAL_HOST variable used in many docker-gen-based frontend implementations of edge servers for SSL offloading, load balancing and reverse proxying.

Here we assume to move forward of turning libre.sh into a sane convention of running web services and alike in containerised environments.