Show what process is occupying ports we want to use

[rwstauner]

to help people debug.
This would probably involve shelling out to lsof and/or ps and might be different for mac vs linux.
If you have another process using *:port docker will fail instantly when it can't bind to the port.
However, if you have a process using 127.0.0.1:port docker will work and then when you try to connect to lvh.me it will use the process specifically sitting on 127.0.0.1:port (it will go to docker only if there is no conflict).
This situation is much more confusing than "docker won't start".