Use empty string when no ports to prevent "undefined"

If a task is not assigned any ports, it currently prints the string
"undefined" after the hostname since the portsString var is not
initialized:

    hostnameundefined

Assign portsString a blank string so tasks with no ports print just the
hostname:

    hostname
Conflicts:
	src/main/resources/assets/js/dist/main.js
	src/main/resources/assets/js/dist/main.js.gz