Don't show ports when there are no ports

[joestump]

Currently the app shows 0:0 when there are no ports exposed. Very few of my containers are exposed via ports as I use caddy-docker-proxy.

[lllllllillllllillll]

Fixed in my latest commit: c1d0a30
It will be included in v0.70. (You won't be able to create a working build out of /dev branch at the moment though.)