treehouses services <service> size (fixes #766)

[kjong]

Fixes #766

root@kjong:~/cli# ./cli.sh services pihole size
146M
root@kjong:~/cli# ./cli.sh services moodle size
148M

[vmnet8]

pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services netdata size
87M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services mastodon size
276M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services couchdb size
unknown service
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services pihole  size
146M

pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services kolibri size
203M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services moodle size
148M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services nextcloud size
240M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services ntopng size
146M

pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services planet size
26M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services portainer size
167M
pi@treehouses:~/git_repo/cli $ sudo ./cli.sh services privatebin size
167M