Include more lines in the list of processes

[idvorkin]

Currently fkill-cli is only listing 4 processes, but the screen can be much larger. Any reason to only list 4 lines?

[sindresorhus]

I was waiting for SBoudrias/Inquirer.js#492, but that doesn't seem to happen. So PR welcome for this. I think we can set it to a few rows less than process.stdout.rows.