remove single client option
remove printf
fix bug with backend and frontend urls

that are sent to client.
associate subdomains by default

Earlier if no subdomain was requested an entry with empty string as key
would be made.
fix bug with getting id for host
fix bug with deregistration
deregister client on connection close.

Reads from the connection, every 2 seconds. If connection is closed,
deregisters the client and cleans up the connection.